it could mean a pile of things. like someone already stated.

BUT my guess would be that he is probably in an enclosure that is too small for him. These are rather large mobile snakes UNLIKE a compact docile ball python. Some people do toss carpets into tight fitting bins, i DONT, and have NO issues with mine.

I house my 2 granite females that are 4 foot long in 4x2x2 enclosures with cypress mulch substrate AND provide climbing branches. Which they use all the time, as a matter of fact they spend about 75% of their time on them and about 25% on their hot spot. Be sure that his temps are good and that there is a gradient within his enclosure. Aquariums do NOT hold humidity too well. Also be sure that his enclosure is not in a high traffic area.

Hope some of this helps.