That's what I was going to say.
Bowing is kind of cool.
Back in the day, it was definately not classless to bow and was actually classy. Who knows what a kid is thinking today though when he bows.
I like it better though than drawing other unnecessary attention to yourself after you win, maybe like holding your arms up in triumph and jumping around (which is ok too and kind of normal and accepted) or something else that is silly or ridiculous or worse, derogatory/unsportsman like.
After actors, and others, do a good job, they take a bow. It is kind of a subtle way of saying, "yes I did good, thank you for cheering for me".
But this is just my thoughts and perception, my opinion.