overbite, is it normal?

I just purchased a Jack Russell and noticed a noticable overbite. I have no intentions of not keeping her, but I can't help but wonder if it is from poor breeding or if its normal, and her lower jaw will "catch up" to her upper jaw.
The idea of buying a JR with a flaw doesn't bother me in the least, but if it is a flaw, then should the breeder not be told? and can I show her still? should I have paid full price?

loving my puppy flaws and all,