Dana's a little preoccupied, but the possibility that this perception whatever isn't just affecting her gets her attention.

The guy seems nice enough, trying to reassure her, and she smiles at him.
"Thank you, that's very kind of you to say. It... sort of happened before I came here, though, and I half expect to just walk through a doorway one day and be somewhere else again."

Dana feels fairly self-conscious dumping her anxieties on a stranger, who looks like he has problems enough of his own, so she clears her throat and stands up straight. "I'm...I'm sorry," she offers, "if you needed to be alone, I could go. I probably should go, actually, I don't live here and I'm probably not supposed to be here." She's hedging her bets, admitting that she's not part of this "faction," but a guy who's having an emotional meltdown alone in a hallway is probably not a threat to her.