Yep, they spring it on you by giving you your 'Employee Handbook' or something on your first day, after you accepted the offer and relocated and whatever else you wanted to do, then sit down to sign paperwork on your first day and.... yep, there it is, that sneaky little non-compete. You ask HR about it and they'll probably just say "It's standard legalese, everyone here signed it, it's no big deal, just sign the damn thing, or you can walk."

You have to bring it up in the interview if you don't want to be bound by one. But even just asking could spook out the interviewees and get them to pass on you "Is this guy a Snowden? Is he going to steal and leak all our preeeeecious 'secrets'?"