Someone I'm a huge fan of once tweeted to tell me they were going to say hello to me after a concert in L.A. Long story short, they never showed up. Needless to say, I was heartbroken.
I have to admit I'm guilty of this. Saw The Best Man over the summer and Ben Vereen was there. *I was in the boxes, he was in ORCH C on the aisle*. I went down at intermission and he was being very chatty with the people around him. Introduced myself, *he then called me King Rob for the rest of our conversation". Asked for a picture which he obliged most graciously. I think that it what matters is the way you approach someone. I'm not sure who it was that said it, but I agree that if you're famous/pseudofamous/etc. in a theatrical setting then you have to have a certain level of expectation that someone will recognize you and will probably at least say hello.
anything you do let it come from you and it will be new.