Bucky watches Sam as he moves but he doesn't step back or otherwise react like he might once have, back in the earliest months since escaping HYDRA's leash, back when he'd been more like a feral animal or malfunctioning machine than a man. He's gained a lot of ground since then.

He nods, acknowledging the next offer the same way he did the first. In all honestly he probably won't, it'll take Sam approaching him some more first (likely if he visits Steve in D9, given how much time the former-asset spends there), or Bucky trailing in on Steve's heels to get them to that point. The fact that Sam made it though isn't something he'll forget, heaped in with all the other small acts of kindness he's received from men and women he barely knows here. "I'll remember."

Now Bucky steps away, not turning his back on Sam but signifying the conversation is at an end as far as he's concerned, barring any closing statement Sam might want to make.