It's almost guaranteed that your puppy came from a puppy mill...about 90-95% of puppies in pet stores are products of such large-scale breeding operations. Please don't beat yourself up...you now know what you didn't know then, and quite frankly, you'll probably never know your pup's exact lines, parentage, etc., because chances are, the miller doesn't know either.
What I am curious about, however, is the health guarantee or warrantee provided to you by the pet store. Most of these "guarantees" that pet shops offer are completely bogus, and do NOTHING to protect you in the event your pup has a hidden genetic issue or health problem that's yet to surface...it is MANY a pet store pup's owner, who has purchased an $800-$1200 puppy, only to have it turn into a $6000 puppy, once all of the health issues have been addressed...this is also another testament to puppy mills, and the complete absence of veterinary care, or pre-breeding health screenings in these places. Very sad.
We all want you to love and enjoy the heck out of your new puppy, irregardless of where he came from, because he, like every dog, deserves a loving home. But if you do decide on another dog or pet in the future, I'd encourage you to adopt. Not only will you be saving a life, but adoption decreases the whole "supply and demand" concept that keeps the puppy mills running.