I haven't had that happen, but it would be refreshing. I would be really weirded out by a "sir" though. casual environments where people can just work and not worry about wearing a persona are nice.
I think the use of "sir" depends on the person's background culture. If you're from the US, it's probably too formal unless you're in the military or something, but other cultures place a higher value on respect for authority. I've had people not originally from the US call me "sir", and while I make sure they know they don't have to, I also don't worry about it.
I would also be weirded out by sir. I say dude a lot but I wouldn’t throw that out like a nervous tic in an interview—it’s a little too familiar and doesn’t exactly reflect situational awareness.