Not very nice of your BL to just take more, than he was told you would get, and then not even ask if that was a mistake.
Reminds me of a time recently where I went to the gas station and the clerk gave me too much money back. He was so certain that it was the correct amount and I recounted twice and told him to check again. Then he noticed his mistake and I gave him the money back. I'm a student, I would take all the money I can get, but I'd feel bad when it's money that I haven't earned.
So you could argue that maybe you earned it because you pulled in a good crowd, and therefore deserve it, but managing a small establishment like that isn't a cake walk either, and you can't even be sure that the crowd came there for you guys specifically, or stayed/purchased because of you. Even if you think the owner was rude about it, doesn't mean that you guys have to be rude and petty about it.