I left a mouse wrapped in a paper towel on top of my BPs cage one, and he came out directly under it and stood up like he was a cobra! My boa does the same thing every time the cat gets on top of his.
I'm no expert, but just an idea... those dimensions are of a 55gallon aren't they? From what I have read on these forums, the bigger it is, the more it could stress out your BP, especially a little guy.