Jack considered whether he should pass it off as a coincidence, or if he should try to explain the Mitchell/Lauren connection. He wasn't comfortable with it himself, and he doubted Rose would do any better, so --

"I think it was a hangout for them," he said quietly, and changed the topic. "I did something stupid, Rose. I tried to talk to the bad vampire instead of helping the girl who was dying. George helped her, but -- maybe I would have done something better."