Giving something that a person already owns back to them can actually make a great gift, under the right circumstances.
Such as if they lost the item in question and are desperate to get it back somehow.
Or if they think they lost it, but you actually stole it so you could give it back and receive their eternal gratitude...
Commentary by memnarch (who has not seen the movie)
I guess Finn didn't want to have that for long then, huh. I wonder why. Maybe Poe is actually going to get sent out at the same time in order to get Rey to come back, and this is the way to let her know a ride is coming? I'm not sure if that'd work that well with the fleet still after the Resistance, but it'd be something for Poe to do. Jim would be incredibly unlikely to just sit and do nothing, but if he's busy next session, maybe this scene was originally something like: "Hey, Leia dropped this earlier. Could you give it back when she wakes up?"
Ahhh, planning. That can be a lot of fun to do. Sometimes it's even more fun than actually doing the plan! Though sometimes, that's because the plan got tossed out the window as soon as the enemy showed up. For something like a casino heist, that would at least require some preparation on the GM's part. Maybe not plotting out an entire map, but having something more than just a one-room spaceship so it doesn't immediately balloon into a 10 million mostly-droid-populated cruise ship. Though that would mean there's potentially a lot of money to be had! And plenty of potentially armed guests as well...
Finn: Here, I don’t think we’ll need this.
Poe: What is it?
Finn: Decoder bracelet. Encrypted communication wth Rey. It may come in handy for you.
Poe: Yeah! I can use that as a courting gift for Leia!
Finn: It’s hers. She dropped it.
Poe: She’ll be even more pleased to see it then!
Finn: Whatever. Rose, BB-8, let’s go.
Poe: Contact with her child. What could be more precious?
GM: All right. I think we better break for the night here.
Rose: We want to do the casino heist!
GM: Don’t you want time to plan it out?
Rose: We’ll make it up as we go!
GM: Yeah, and if I do that you know who won’t enjoy it?