I see nobody has replied for a while, so let me add that there is still no state "registry" or questioning by the state. Yes, you should make sure your instructor is actually a certified instructor. That means certified by a national organization, (think NRA, or probably now USCCA, since they now do certifications). Sheriff Justin Smith hasn't questioned any of my credentials or students to date.
That being said, I haven't had a single student ask for my credentials, although my NRA instructor number is on my certificates, and they can always check with the NRA for the info.