JC's default setting is F&F - fun and flirty. And she does it so well, I think that's one of the reasons she's so likable. She was just as F&F on The Martian press tour as on CP's.
You're right, she's not making it seem like a thing - others are.
Slightly unhinged fan on TH and ALL of his female co-stars: They were meant for each other. Oh, their babiezzz will be butiful!!