I had upper eyelid surgery 16 days ago and on the 13th day the stitches were removed.

The type of suture used can determine the timing for when sutures are removed.  It is also not unusual to see some tiny bumps along the incision line in the first few weeks after upper blepharoplasty.  You should contact your surgeon to discuss your concerns so that you can be examined in person if needed.  

Medicine is an art as well as a science.  There are always individual variations which require changes in routine.  Dissolvable sutures are not removed on the 7th day and allowed to come out on their own.  This is the reason why not to place the opinions of "Dr. Google" over your own doctor.  If you have questions, you should always consult with your doctor.

Most surgeons take out the sutures anywhere from 4 to 12 days post-op.  It varies quite a bit.  If they are dissolvable sutures they may not even take them out.  Some patients will get small lumps everywhere there was a suture.  They are not keloids which are not seen in the thin eyelid skin.  You can form a hypertrophic scar, which is a raised thicker than normal scar, but it is too early for that.  And some people will get suture tracks which are small elevated areas of skin where the sutures were. Most eyelid incisions heal very nicely so just be patient.  A little massage will help to flatten it out.  If you get some suture tracks they can be opened in the office.  

The length of time will vary greatly. It is still very early so I wouldn't worry about abnormal healing at this point. Give it some time and continue follow up with your surgeon. Best of luck