I consider the salute to be a sign of respect...which is why I do it whenever something (like a song) makes me damn proud to be an American.
I saluted when I heard Toby Kieth's "American Soldier", I saluted when I heard "Have You Forgotten", and I've saluted to dozens of patriotic songs that struck the patriotic choir in me. It's meant to be a sign of respect towards the song and the person who sings it.
You know, it always puzzles me how people make big deals out of little things. Sure, the meaning behind the act of saluting is no trivial matter, but it's hardly something worth starting this kind of debate over.