For dog breeders on Yahoo answers?

Unusual, but not unheard of. Sometimes things come up and you just need to be somewhere other than the computer. What I don't like is his question about breeding. Are you buying a working line or show line GSD? If show, then unless you're purchasing a show prospect, the only thing he should be asking you is you're aware that the puppy needs to be s/n at a certain age. If there's no situation that is keeping him from responding, and the conversation was clearly not over, I'd be a bit wary as well. Give it a couple of days and if you haven't heard from him feel free to email. I'd never leave a prospective buyer hanging & would certainly expect them to initiate contact if I hadn't been able to respond