They should roam and try to escape sometimes though right? Mine tries every couple days when I'm feeding the geckos or tending to the beetles. He's a good eater though...he was roaming and trying to escape before his feeding last night.
If they feel safe, they should not try to escape. My snakes will occasionally take a quick spin around their tubs, but nothing more then that, no pressing their faces in the corners or scaling the walls.