A bite shouldn't be of any concern. It's not a healthy issue. I would check to see if all the puppy teeth have fallen out. I always recommend when you take them in for a spay and neuter to have puppy teeth taken out so the permenant teeth can come in. An overbite or underbite has no effect on health
I place puppies with an undershot bite into a pet home because in the show ring it's penalized and to show we want a scissor bite or a level bite.
Donna Bird
Brooklynn's Yorkshire Terriers