Or it could be holding it in for 3 months... Ball Pythons are weird that way. Some do it regular weekly, others just make a big mess after a few months. Doesn't means there is anything wrong with the Ball Python, I don't think. I know a few local breeders that experienced this with healthy Ball Pythons as well. It is just one of their quirks.
Edit: By the way, boas do the whole variation on when they crap too.