In my opinion, if you have no plans for breeding and you don't feel comfortable doing it without possibly hurting the animal, then no need to sex it. There's no real need to if you don't intend to breed, plus care requirements aren't any different between males and females.
Another thing, I was picking up substrate a few weeks ago at a petsmart, and got to talking to an employee about a pastel they had (just labeled as "fancy ball python"). She said that most petsmarts, at least in my region but maybe its a nation wide thing, only carry males. I guess their suppliers want to keep their females for breeding and they need less males, so its cheaper for petsmarts to get all males.
Like what Petco does with rodents...you have to beg them to special-order a female. They want you dependent upon buying from them, not breeding your own.