I'm sure he's getting choked up. When sings and plays he is so so deep into what he's doing it can get to him. I know this because I get choked up when I sing or play really good stuff and... umm... harry kicks my rear end for being a good musician. You do the math.
If you are into classical stuff, get a copy of Telemann's concerto in D for trumpet, harpsichord and orchestra... the adagio movement.. man, that piece gets me going when I play it.
For singing, Jill (BLRL) always gets me going.
I guess I'm just a duck at heart