I have experienced bruising in the groin several days after gynecomastia surgery. Is this anything to be concerned about?(photo)

The bruising will probably not amount to anything significant, but that is a very long way for blood to trickle down if the only area of surgery was your chest.  I would suggest visiting or calling your plastic surgeon to get his or her opinion on the matter.  It's possible that something else (your garment, a strap from the operating table, etc) may be responsible for the new bruising, and your surgeon would be the best one to sort this out.  

BRUISING AND SWELLING: Bruising and swelling are normal and
usually increase slightly after the removal of any tape or foam. The bruising
will decrease over 3-4 weeks, but may last as long as 6 weeks. The majority of
the swelling will be gone within the first 3-4 weeks. However, it may take 6-9
weeks to disappear completely. The compression garment helps reduce the
swelling, and the longer it is worn, the more quickly you will heal.

NUMBNESS: It is normal to experience numbness around the areola and
chest. As your body heals, you may notice random bursts of pain in your chest.
This is usually a sign that the numbness is subsiding.

LUMPINESS: As you heal, the area may feel “lumpy”
and irregular. This, too, decreases with time, and massaging these areas will
help soften the scar tissue.

ACTIVITIES: If your work keeps you sedentary, you
may return whenever you feel up to it. If your work is strenuous, wait until
your work activity does not cause pain. Wait at least 4 weeks to begin aerobic exercise.

As with all operations, pain and discomfort varies greatly from
patient to patient. Generally, one should expect that pain medication will be
required for the first several days. Continuing discomfort can last varying
amounts of time.

While it is normal to have bruising at intervals for months after surgery, you may want to have the bruises in your groin area examined by your plastic surgeon or physician unless, of course, there was some sort of injection, anesthesia or other needle used in that area for your procedure. In that case you should give it a little time to heal.