I remember that a Nat Geo documentary said that he hid away due to a conversation with Limbergh who said that fame will do horrible things to a person. I like that he comes out of his shell once in a while, and provides the ages with his own perspective.
Armstrong had always been known as a very private person who hated the spotlight. Even if you watch old pre-mission films, you can see that he doesn't say a lot and is very economical with his words. Buzz Aldrin, on the other hand, was always far more outgoing and outspoken.
I am presently reading the book "Rocket Men: The Epic Story of the First Men on the Moon" and it provides a very detailed and fascinating look into what was going on behind the scenes in the days before, during and after the Apollo 11 landings. I just finished the chapter that dealt with the "First man out controversy" which was based, in large part on the personality differences between Neil and Buzz. It's a really good read that I highly recommend.