Under bites happen however this type of things if a breeder chose to sell the animal should be disclosed prior to the purchase.
Now in some cases it is severe enough to prevent the animal to eat on it's own but this is obviously not one of those cases considering it is not that severe and considering the weight of the animal that shows that the animal was eating.
So there are two issue one is the one of a breeder with poor ethics selling an animal with a birth defect the second is you having issues getting your animal to eat which is common with new owners.
Here is what you need to do to a T https://ball-pythons.net/forums/show...-hatchling-101
Now when it comes to the breeder it's a whole other issue, yes it should have been disclosed but you should have inspect the animal upon reception as well and with 2 months that have gone by I am afraid that you will have very little recourse but you can always try.