Everyone has their preferences, but if they would give up a puppy just because it is black then they shouldn't have gotten a black one in the first place. I mean, usually when someone has a color preference in dogs they buy the color they like, not the one they don't like. Sounds like they're not even ready for a puppy/dog anyway. But I wouldn't take it personally. It doesn't sound like the person was attacking your preferences or your dogs, just stating that s/he doesn't like them as much as the yellows. Personally, I have always loved the black labs. But I really do love them all, so it wouldn't matter to me which color I got if I were to get one.

Still, these people sound pretty irresponsible.