Can't say anything for certain without pictures...might be axanthic, although it's highly unlikely that someone would just give one up or sell one for a normal price. There is a tremendous amount of variability just within the "normal" range for ball pythons in both colors and patterns. But if YOU really LIKE that particular snake, there's nothing wrong with going for it...and maybe someday you can prove it out to be something genetic. (Only way to ever know for sure in these cases is to prove it out by breeding)

Good luck with it!