Thank you for your question. The only risks from that would be bruising, discomfort, and possible swelling. It is nothing to be too concerned about. wait until swelling goes down to see your full result and then go from there, if you are still concerned. Best of luck!
Dhaval M. Patel
Double board certified
As you are only about 10 days after the surgery, the punch on your buttock, gives you more swelling and discomfort that may not be a serious risk for the survival of the injected fat. You still have to wait for the swelling and discoloration to go away, to see the final results from the procedure.
It is unlikely that if your butt was slapped that you had any significant trauma to it. If concerned, it is always best to see your surgeon.