The Sarah thing was already known. Coil addresses her as Sarah Livsey in her interlude, and she says she’s willing to answer to either that name or Lisa Wilbourn but prefers Lisa these days.
The “Sarah thing” from that one ask is, I assume, the fact that Lisa was previously named Sarah Livsey, which was revealed back in arc 8. I can’t think of any other Sarah things it could be.
Ahh, right!
Here’s the thing: I remembered well enough that Lisa had changed her name. But I did completely forget what her previous name actually was.
(I know, I’m a disgrace to everyone who calls Lisa their favorite Undersider.)