One of my Cockers had an overbite when he came to me at 10 weeks. As he grew and as his adult teeth came through it disappeared and by about 7 or 8 months old he had a normal scissor bite, which was just as well as I intended to show him!
He was a younger half brother to my other Cocker and I knew the breeder quite well. I know that neither of his parents had the problem and had normal scissor bites, because I saw them!