Does he have at least 2 hides (one on warm side & one on cool side)? and what kind are they? how big are they compared to the snake (if he was curled up)?
Most snakes prefer a snug feel...only one doorway that's not too big, just enough room for snake with a meal-bulge to fit thru. Hide shouldn't be too tall either-
if you look at House Beautiful magazine, homes w/ big dramatic front doors & high ceilings...snakes want the exact opposite. If he's roaming it's possibly
because he isn't finding a place he feels safe to settle in. Be sure the surface temps. INSIDE the hides are ok too, not too hot...heat can build up.