Whoever told you that he/she was "too old to sex" has no clue what they were talking about...
In my experience sudden changes in behavior almost always are a result of improper husbandry...
Check out these threads to make sure that you are doing everything correctly.
http://ball-pythons.net/forums/showt...ius)-Caresheet
http://ball-pythons.net/forums/showt...04#post1845904
Finally Ball Pythons do not "enjoy" or "love" being handled... most will tolerate it, but they would much rather be tucked away in their hides.