It's not just a random oddity, Tony's dislike of people handing him things. There's some deep-seated childhood trauma that goes along with it, he just doesn't talk about it.

He taps his fingers against the bottle, getting a sense of its dimensions. Once he has, and he's confident he's not going to pour it all over himself, he takes a drink, not realizing until then just how thirsty he's been.

"Thanks, Steve. I owe you one."

The ones he owes are slowly beginning to pile up. He hopes that soon he can start paying some of them back.