Yeah to everyone I've met in the past year, I assume the non-gamer position unless it's completely obvious.
I do this too, though I'm openly geeky to geeky friends unlike Retro. Though it'll sometimes take a few weeks time until I'm convinced someone is geeky, and only then I feel safe talking about something like mainstream games. And probably months to start talking about Dwarf Fortress or anything indie like that.
The weird situations are the conversations with geeky
and non-geeky people. Even if it makes me feel a bit bad sometimes, I act really non-geeky in those, which I noticed as one friend from school I've known quite well for three years surprisingly said she had a hard time imagining me playing much at all. Also, I have a friend who hates video games (and geeks to some degree), so I guess I do a good job at covering up my gamerness.
Having been playing the drums since I was 11 probably has a lot do with that. It makes the general image most of people have of me something like: "That weird drummer guy who does well at school and talks a lot", instead of "That weird guy that does well in school, talks a lot and has strange longish hair."
I'm sure everyone is a social chameleon to some degree, but after a certain limit it starts to feel a bit wrong. Occasionally I wish I didn't have friends that cause me to avoid using weird words or telling geeky jokes, but then again that wouldn't leave me with many friends.
EDIT: This analysis was written by 1am LASD, any views expressed here might or might not be shared by 10am to 10pm LASD