Because you don't know me. I don't expect you to trust a stranger so easily.

[Part of that is just the reactions he's gotten from the other slightly familiar faces. Steve is under the impression that other worlds' heroes have a lot of trouble trusting even those that should be heroes and allies to them. He's trying to play by their rules. And, of course, he isn't sure how much he can be trusted.]

I'd like to earn it. To know that it's deserved.