Inbreeding is something that I think you better have a lot of knowledge of your lines of to do (talking 15-20 years of dealing with them) as it can be great for bringing out all the positives but it can also be a trainwreck for bringing out all the bad stuff in a line. It doesn't mean your pup is going to have issues or that you should return the pup but perhaps asking why they inbred so heavily, what they were hoping to accomplish, getting the full details of all health testing done on as many of the dogs in the pedigree. I am not familiar with most bully pedigrees so can't help with anything in that regard but hopefully some breeders or enthusiasts will chime in.
+1 to all of this reply ... and I'll add / re-emphasize ...
It really depends on the quality of the animals behind your pup. If they were DNA tested to be free from the ailments common to your breed ... and ... they were otherwise tested for hips, elbows, eye, and cardiac issues that may not be DNA-tested (at this time) ... and all of the animals in question (parents and grandparents) passed, then I wouldn't have too much of a concern.
...however...if that's not the case, then I'd say the odds go up that you'll have a problem...
BUT -- that's no guarantee you'll have a problem either.
Talk to the breeder, do your research, ask your questions and follow your gut...and remember, if you keep your pup, and there is a genetic / health problem down the road, it's not the pups fault, so don't take it out on them. You're in a tough spot and its unfortunate you're having to deal with this. Good luck with your decision.