Finch knew that his suspicion was justified as soon as the woman rested her hand on his briefcase, offering to carry it for him. This is why he doesn't trust strangers. Or, really, anyone. But his lack of trust was so very justified, no?

"No, thank you," he declined firmly, trying to remain polite and calm but it was difficult to do so when everything was so irritating and you're surrounded by idiots. An ever so slight scowl crept up on his face as he heard and saw a couple laugh under their breaths. No doubt it was at him—and that angered him even further. He can't let this woman make a fool out of him.