How do you feel when you met someone who might be trans ?

[Medusa]

I want to ask you.
How do you feel, when you met someone who might be trans ?

For example yesterday in a bus I sat next to two guys chatting, but when I begin to listen  one of them use female pronouns, and when I look at her, there was just a common girl, I was little confused and have urge to stare or even to ask (I'll never have nerve to ask, but I want)