I think if a beardie was in pain from falling he would have stress marks and possibly a black beard. Also may be limping or acting a bit funny. Seems if he is eating and pooing fine, and also acting normally that he should be ok.
How far did your little guy fall? He may be fine, but I would suggest keeping a close eye on him, since it's only been a few days since the fall. Beardies do tend to hide the fact that they are hurt or feel pain. Just keep a look out for any odd behavior, but he's probably okay. Those little buggers are good at leaping off of things. They do know how to keep us guessing and worrying, don't they?