I can't understand why people get so wound up about being called "mate".
Most the time its used as a term of endearment or respect, and not because they think you are a friend.
With some people you would have thought you'd have called them a **** or something.
And 99% people who hate being called "mate" will never bring the person up on it, mainly because they know it could offend the other person, and moreso, deep down they know that they mean no offense by it and that it is a term of endearment/respect.