Mine sort of does this, but he's not so crammed in and he sort of sits on top of it with some of his body behind like your's. He did it for a long time and I think he just didn't figure out his hide, yesterday was the first time I saw him inside of it (and now he loves it), but he still likes to hang out on top sometimes. Is he still going inside of his hide, and did he before? If he's not then I would totally agree with Ax01, or suggest that he perhaps hasn't noticed it yet.