I agree with Su. Ki's answer. I just want to add that he might of said it jokingly. When given an order, soldiers/marines reply with 'Yes, sir,' For example, you asked him to move for you, and he might have said, 'Yes, sir!' in a teasing way to show he was following through with your request.. Do people do this often? No. Should you take it personally? No. :)

How is "Yes, sir" used? As a polite way of addressing a man. Do you use "Yes, sir" even for a woman? No, never. I can't think why your fellow passenger would have said 'Yes, sir' to you. Looking at your photo, I can't believe he could possibly have mistaken you for a man. Perhaps he wasn't a native speaker, and he didn't realise that 'sir' is only ever used for men?

"yes, sir" can only refer to a woman when it is said ironically to show that the person is being bossy, too bossy. I think Su. Ki. is right, it must have been a non-native. Although...look here: http://www.urbandictionary.com/define.php?term=yessir I have never heard people say this, anyway