What was the popping noise I heard when I massaged my raised incision and why is it flat a few minutes later? (photos)

When we are closing an incision we place sutures along a line a little wide of the incision. The sutures are then tied and this creates a small ridge at the incision.  This ridge takes the tension off the incision itself and let's it heal better.  When the sutures dissolve the ridge flattens.  These internal sutures slowly weaken over weeks or months and then the "ring" of the suture breaks.  A vigorous massage will sometimes break the suture ring, releasing the ridge, and allowing the suture to flatten.  If this occurs several weeks after surgery it's no cause for alarm.

Hello,You broke some internal sutures, which were causing your skin to be raised. You did not do anything wrong. Best of luck!

it suggests a suture was broken resulting in the 'popping' sensation and if it wasn't a suture, it was the scar tissue being separated to allow the scar to flatten.  But you should always check with your surgeon since your surgeon knows what exactly was done and how it appeared prior to your episode.