Calling me "sir"

[Ryo Hazuki]

I held the door open for a average sloot today and she said "thank you sir". She treated me like I'm someone would treat their elderly grandfather. I'm only 22 I would gues her to be about 19. Was she trying to patronize me or was it a genuine sign of respect?

In the very least, it means she perceived you to be an "elder" as opposed to a peer.  Do you look older than your age?