I know, I know... kids shouldn't sleep on their tummy... but he sleeps on his tummy. So, surprise, surprise... when I went to get him out of bed--he wasn't on his tummy. He was silly with smiling too. So, no one has seen it yet... but the kid must have rolled! I tried to get him to do it again... but he just pushed up pretty far on his arms and shot me a pretty funny look.