Not for me. Not in Safari, not in Firefox. Care to take a screenshot and tell me what you did to get them? (Actually, I think I'd prefer them to stay as they are, anyway...)
I was about to say that they've always been native aqua buttons, but then I realized that they're only native aqua buttons in plain HTML view. If you use their fancy-pants normal mode (I don't), then you get nasty Windows-esque buttons. Go figure.