My sister in law bought a chocolate lab Christmas of 08 for her daughter. She has hip dysplasia and was told there was nothing they could do for her. I didn't know some breeders x-ray for that.
The description from Lorraine and WinstonMom is exactly how this played out. The pup was fine then developed a limp that didn't go away.
I've decided to ask my vet what he thinks I should do about approaching the breeder. On his advice, since he knows them well, I'll either drop it or pursue it. Either way, I'm not giving him back and I don't think I want another puppy at this time. They are a lot of work!