I'm curious, when you say that, do you mean that he doesn't have that "rockstar" attitude, for lack of a better description? Or (and this is my experience meeting some master musicians) he doesn't come off as like being an ultra introvert who only cares about music/playing and is not "normal"?
Everyone "famous" I've met, other than Michael Romeo, fit into one of two categories: 1. Boisterous and driving the conversation (not necessarily in a negative way, type A people can be a blast to be around) or 2. Aloof and withdrawn from the conversation.
For example, when I met Charlie Benante (drummer for Anthrax), it was a blast. He was cracking jokes nonstop and generally being ridiculous. When I met John Petrucci, he wasn't loud or anything, but he was gleaming with energy and still doing 90% of the talking. On the other hand, when I had met Victor Wooten, he just wanted to be left alone and not interact. When I met the guys from Symphony X, they seemed genuinely interested in listening as much as talking. It totally took me off guard. Granted these are all snapshots at very specific times and situations, not like I know any of these people on a personal level. It could well be that one person could meet a "famous" musician on a good day and have a good experience and then the next person could meet them on a bad day and it could be a total drag.