Robin rolls her eyes at 'just a couple nights' and 'won't be here much'. She stands there with her arms crossed over her chest in that way that says 'I've already figured out something you haven't.'

It wasn't a new pose.

"So you find the missing Billy Hargrove, at your ten year reunion no less. You walk out of said reunion early so you can go grab coffee with him. And now he's staying here. By all means, him not staying in a shitty motel is a win, Max will worry once she realizes what is going on. But here?"

It wasn't even a 'he beat you up once' thing. It was an 'after all you learned about yourself are you really going to put the forbidden fruit in arm's reach'?