4 weeks post op, I have popping sound when I sit down and accidentally leaning on arm. Is this normal?

If no swelling or malposition occurred, then the popping was likely of no consequence.  Call your plastic surgeon and discuss being seen in person if you have any concerns.  Best wishes and take care.

Yes, unfortunately at 4 weeks postop capsulorrhaphy, the popping that you heard may be sutures breaking. Hopefully, this is not the case or enough sutures were used so that there will not be a recurrent breast implant displacement problem. Best to follow-up with your plastic surgeon who will be in the best position to provide you with an accurate assessment, recommendations, and (hopefully) reassurance. Best wishes.

Dear Sunny,Thanks for your question. Without an examination it is impossible to tell exactly what happened but it is likely that you popped some early scars in the pocket and maybe some of the stitches at the capsular repair. Hopefully this has not damaged the repair and allowed your implant to fall over into your armpit again. You need to return to your surgeon for an examination soon and it would probably be a good idea to stay in a supportive bra until your questions are answered. Good luck.