Are there some cases where SMAS tissue doesn't soften after facelift?

In general, one of the limitations of surgery is unpredictable behaviour of the scar tissue. It can build up more significantly in some areas, and if those areas are generally mobile, they will feel stiff with movement.
Another possible explanation is a mild chronic pain problem, which is due to how our brain responds to changes in the peripheral nerve connections that follow the surgery. Depending on how disruptive the problem is, a consultation with a pain specialist may have some benefits.
In general, scar tissue does tend to soften naturally and injections of steroids to accelerate the process tend to be more problematic in the cheeks, so most surgeons would not feel comfortable using them.

The firmness you feel is not the SMAS, which is a thin layer of tissue and not significant down in the neck.  The firmness generally represents swelling of the tissues and scarring.  Early on, more swelling, later, like 13 months, scarring.  Massage helps scarring.  Other less common reasons for persistent swelling could be inflammation from glands injured in the area or lymphatics that were interrupted during the facelift that have not re-established themselves.  There is no surgery to correct these things, only time.  It may be another year with some massage.  Hang in there. 
Dr. Z

Yes, it is possible to still have inflammation 13 months after surgery although it should be improving significantly at this point.  The signs of inflammation are redness, swelling, tenderness, and stiffness.   A general rule of thumb I use is that if the scars are still red then there may still be some stiffness.  ALot depends on your symptoms.  Do you have jaw pain?  Could it be what was known as TMJ syndrome now known as myofascial pain disorder?  This is why it is important to discuss with your surgeon.  Good luck

 Hi, I have many SMAS performed facelifts and neck lifts for over 30 years and for the past 15 years have performed many minimally, invasive SMAS facelifts.  Non smiling photos of your face from the front and sides will help in the evaluation.  The SMAS is a very thin muscle layer just below the subcutaneous fat in the face.  The stiffness might be due to increased scar tissue formation under the skin.  This can be due to an extensive tissue undermining, oozing and bleeding in the tissue spots op or from increased, persistent swelling within the tissues nor injury to the SMAS layer itself.  The photos might shed some light on the subject but massage is likely your bets option of softening the tissues in the affected areas.  Of course, this is best avoided in the first place by less invasive tissue dissection, meticulous cautery of all bleeders in he surgical area, avoidance of blood thinners pre op and for 3 weeks post op, and limited strenuous activity post op.  The greater the degree of tissue dissection, the more theses rules will affect scar formation.   
  If you have "jowls” these are sagging facial tissues and the primary indication for some form of a SMAS facelift.  The underlying SMAS layer, of the face, must be dissected, lifted, trimmed and re-sutured (not merely folded or suspended with threads or sutures that will not last).  The excess skin is then removed and the facelift incisions closed.
 My most popular SMAS facelift is the minimally invasive, short incision SMAS facelift that has all the benefits of more invasive facelifts (traditional, mid-face, deep plane, cheek lift and subperiosteal facelifts) but with these added benefits:
very small incisions and no incisions extend or are placed within the hair.
minimal tissue dissection = less bruising and swelling = rapid recovery ( several days instead of weeks or months with the more invasive type facelifts mentioned)
can be performed in 90 minutes or less, with or without general anesthesia
no incisions within the hair = no hair loss
excess fat can be removed from the face and neck
excess skin removed from the face and neck
cheeks, chin and jaw line can be augmented with dermal fillers (I prefer Restylane Lyft) or facial implants
most patients fly back home to parts all over the world in as little as 3 days post-op
 I combine facial shaping with every facelift procedure.  When jowls are present, these should be done in concert and not alone or separately in order to create a naturally, more attractive face. Following my beauty principles, women look the most feminine, youthful and attractive with heart shaped faces.  Heart shaped faces have cheeks that are full and round in the front.  Cheek augmentation with a dermal filler or using cheek implants for a permanent enhancement will create full, round cheeks that will feminize the entire face.
 A weak chin creates an imbalance making the nose appear larger, the mid face top heavy and the lower face look short that de-emphasizes the lips and allows early formation of a double chin.  Chin augmentation using a chin implant will add projection to the chin creating harmony and balance to the lower face.   I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick and highly effective.
Hope this helps.