I have seen Both Spinal deformities and Spinal Calcium Growths. on Ball Pythons. The Spinal Kinks are usually something that they have from birth not something they get from weing whacked... or stuck in a drawer, However that is possible although it would proably result in the lower body being paralized.
If its a kink the animal will most likely be just fine as it probably again has had it from Birth. Please however do not ever breed it as it could be genetic.
If the "bump" is not just a uniform raided bump like a kink.. But more like a bunch of rocks on the spine, That is more likely a calcium growth and should be looked at by a qualified vet to see if it is growing and needs to be removed.
Michael Cole
Ballroom Pythons South