We started a new gaming table a few months ago. One of the players is my partner's coworker, so he and I knew of each other but hadn't met until we started playing.

I GM for the group, so for months he's been showing up to listen to me yap and has certainly gotten a good look at me.

We were messaging about something the other day and I made a passing remark about "not being out" somewhere.
Him: "wait, what do you mean by out?"
Me: "I mean they don't know I'm a trans woman."
Him: "Oh, I didn't know you are a trans woman."

That's it, I can die happy.