Just to go back to the OP, I think people are being unduly unkind about the woman who popped the, 'Do you know Mara Drummond?' question.
She's a bit like someone who has a seat on a crowded subway. There's a woman standing up in front of her. The woman has a large belly. If she's pregnant, the polite thing to do is offer her a seat. But if she isn't, offering her a seat will just emphasis that you think she's incredibly fat.
In this case, the other woman she thought she had read you, but she wasn't sure. She didn't want to come right out and say, 'Are you trans?' because (a) it's pretty intrusive if you are and (b) it would totally piss a cis-woman off (sorry to be blunt, but it would).
On the other hand, maybe she wants you to know that she's cool with people who are transsexuals and might even like to have a conversation about the issue, like I would have conversations about race or religion with friends who are Afro-Caribbean or Muslim (or Jewish, or whatever). Or maybe she just wants to know a fact about you which will have some influence on the way she conducts a conversation - if only because she might be more sensitive to your feelings as a transsexual once she knows what the situation really is. OK, so this is a little patronising. But her intentions could be perfectly good and respectful.
Her problem, though, is: "How do I open the conversation without saying something blatant?"
By saying that she knows Mara Drummond she's dropping a hint, hoping you'll respond with the information she wants.
This might seem intrusive - and, yes, what the hell business is it of hers, anyway - but we all use hints and tricks to find out private stuff about other people. For example, two attractive strangers meet in a bar. Things seem to be going well. It's not going to be long before each starts trying to figure out whether the other one is single and/or available. Or ... Two guys have a conversation. One is straight, but he's not sure if the other is gay. Even if he's not remotely homophobic, he might try to get a clue or two - again, just to make sure he doesn't inadvertently say the wrong thing.
There's so much genuine hatred and genuine offensiveness towards us, perhaps we should be gentler on those who mean no harm, but just don't quite say the things we'd like them to ... Tolerance cuts both ways, after all.