Pictures might help.
Sometimes, between shedding cycles, one of mine will make a little bump like almost a couple extra scales bunched up under each other. It doesn't seem to bother them and after a shed cycle or two I can't find them again. But this one is also my rescue burned snake. I don't know if maybe his body is still trying to repair the belly scars and just accidently puts a few extra scales on his spine.... or he's also my shyest boy, so he likes to wedge himself up in a log hide really tight.... so maybe it just as to do with the pressure points since it's always along the spine.
Obviously, keep an eye out for anything your baby may be rubbing up against. The most important thing for now is to monitor it. If anything weird happens, make your vet appointment. This can be any type of growth past where it is now, any fluid discharge, or if it sloughs off and leave an large wound. As a heads up, snakes don't form a liquid pus like we do, it gets to a thick enough point that it doesn't discharge and just encapsulates. If it does become much larger, you may need a vet to drain it or it becomes like a cyst.