[sammyg2]

He doesn't owe anyone anything, especially an autograph.

Who are autograph seekers? They are either pitiful loosers who don't have a life and think that getting someone famous to sign their name will somehow make the looser feel important in some psycho-tarded way, or they are leeches who just want to get a famous person's signature so they can pimp it and get a few bucks.
Either way they are total loosers. (Yes, I know it's not spelled that way. It's a running joke. )

I've met famous people over the years as have you, I treated them with respect and appropriate behavior I would extend any stranger who wasn't a tool. They didn't owe me anything and I had no right to interject myself into their life.
A casual but reserved nod, maybe a subdued hello, and if invited a compliment and a thank you, something like "I've enjoyed your work. Thanks" and leave it at that. I do not believe in acting like a leech or parasite.

In most cases the result was pleasant, and in one case we became friends and had a very long conversation over many beers.