When I watched last week’s premiere episode of this new comedy, about former lovers who impulsively follow a long-dormant agreement, years after making it, and meet on a specific train going out of town, the situation, and their emotions, kept reminding me of something. I couldn’t place it, but the way Merritt Wever and Domhnall Gleeson looked so shocked and frazzled by their reckless impulsivity seemed familiar somehow. And then, finally, I got it: remember the dazed looks that Dust