He's nodding along, not looking the slightest bit confused until the stranger starts apologizing. Mulcahy reaches out tentatively, the slightest weight of his fingers on his arm.

"What for? It's very useful to know what I'm getting into, and I appreciate it."

... A beat as something occurs to him.

"If you're worried that I'm not used to seeing so many strange people from strange worlds, I think you should know that the place we were trapped in before this was very similar in that regard. I'm very used to having to ask people when they come from."