Just make sure you have your driver's license with you when you get to Guest Relations. Also have that if you need to call to get your Annual Pass ID number. It really is a painless process - I left mine in the car and didn't realize it when I got to the turnstyles. Even worse, I didn't have my ID with me either. The husband was already through and into the park. I got him back with frantic arm motions and the Cast Member saw our last name was the same as was our expiration dates on the passes and issued me a new one right away.
That's what I like about APs - I'm so anal retentive about tickets and things like that, I can relax a bit with those.