Ball python, hasnt eaten in a little over 2 weeks

[D70challenger]

Hello,
My friend has a ball python. He is a little concerned because it has been over 2 weeks since his last feeding and it will not eat. He has been trying to feed her about every other day now with no success. From what I gather, it shows interest in the rat, moves up and touches noses, but once the rat makes a sudden move the python retreats as if threatened. He thinks she may shed soon, and that he has heard of ball pythons sometimes going in a month long state of hibernation where they will not eat. Is this true and should he be worried? There has been no changes in feeder size or where he buys them. He said he would wait give her till next Friday before he makes any drastic decisions such as the vet.