Oh, I forgot to mention one more possibility - he has been spending more time with other kids since school started, and I think he's picking up on what other kids get away with saying to their parents. I don't know how to explain to him why that kind of talk doesn't fly with us, beyond telling him that "all families are different." It sounds like a lame explanation even to me, but if I tried to dig deep it'd be a half-hour lecture that would probably make things even worse!