It took Arthur a few minutes to settle up with the bartender, and his disposition as he leaves the bar is significantly different to when he was talking with Natasha over drinks. He's about to walk the other way when he glances back where Natasha and Eames are standing, and he has to do a double-take.

Great.

His shoulders drop forward as he realizes that they've seen him and they've seen him see them and now there's no pretending it didn't happen.