Usually BPs will do this, but maybe he came out of his hide when you were sleeping. They tend to do that, and make their owners worried to make them think they don't come out of their hides

Your BP could also be shedding, so if you haven't really handled it in this past week I think you should check if it's shedding. BPs will stay in their hides the entire time they are shedding until the day they are ready to shed the skin off.