I've only been to our local one once (crappy food, bad service), but I don't remember seeing a sign. It might be a franchise location though.
Here in OK there are no restaurant carry restrictions, only restrictions on carrying into places that predominately serve alcohol. And even if you find an establishment with a gunbuster sign, it's not legally binding. If you're CC'ing and they figure it out (you're doing it wrong) they can ask you to leave. If you refuse, you're trespassing, and that's when the cops can be called.