Question after first time doing anal

A couple of days ago we finally did anal sex for the first time for both of us. He (the passive) pooped just before getting started with it.Everything went good, didn’t hurt him too much and he left my house feeling great. But now, 2 days after that, he hasn’t been able to poop normally. He says that it’s not that he can’t do it, but more like he hasn’t felt the need to do it, and if he tries to force it almost nothing comes out.Is this normal, should we worry?