What are you using to heat the cage? I have seen a lot of threads where a BP didn't like the hot side and was aggressive... most of those threads ended with the discovery that they were using a unregulated heating pad that was way too hot.
Check out this thread:
http://ball-pythons.net/forums/showt...04#post1845904
Do you have a hide on the cool side as well as one on the hot side?