I think President Bush left quickly for a variety of reasons..he was emotional (Reagan is his role model and he adores the man), he wanted to keep it dignified, he knows this is about President Reagan and not himself, he didn't want to hold up the crowds that had been waiting many hours to pay their respects, and last but not least, he and Laura were on their way to see Nancy Reagan at Blair House. He handled it just right.
You mean I missed President Bush? Blast!