He obviously doesn't believe her but she can't really blame him - she wouldn't believe any of it if she were him. And she wasn't going to bother trying to fight him over it. He'd see, eventually, either here or when they got back to the Capitol. So she was very glad when he changed the subject.

"Boston. Well, what's left of it anyway. As far as I know they closed down the quarantine there and abandoned the city after I left. That's what Joel said they were going to do." She paused, having said well more than she meant. "... It doesn't matter. Where were you from?"