yes, this is pretty similar to what I was getting at. It puts you in an awkward position, because if you say "I prefer that you address me as mr. or sir," you sound like a dick. You can try something like "I'm not used to customer service or business personnel addressing me by my first name," but it's still dickish. Bottom line: it's up to an adult to determine how they prefer to be addressed, especially if it's not in a casual setting. I wouldn't address another adult by their first name in a non-casual setting unless they'd introduced themselves that way or indicated that's how they preferred to be addressed. It's like that earlier post that brought up the "friendliness vs. politeness" thing.