Why is it that the principals always punish good kids the worst?

Good advice already! I know just how you feel, because I was a "good kid" in school and then I became a teacher. The teachers know who the good kids are and they are surprised when they see them acting up a bit. They expect more out of you, because they can always depend on you to set a good example. Don't take it hard. Like Danielle said above, go to the principal and say you're sorry again, that you don't know why you acted so rudely when you know how annoying it is when other kids interrupt the practice. (Yeah, pour it on a bit!). Even thank her for reminding you! You'll walk away like Little Miss Goody McGood. I'll let you in on a "secret" -- teachers and principals LOVE to be "ered up", even when they know your doing it. Good luck in band!