That was a challenge; Steve was supposed to be a good ol', honest American boy with dirtier boots than secrets, so Tony had to assume that Steve was confident in his card to bait him like that. That twinkle then was curiosity, which he tried to play off by lounging back on his free hand like he was even capable of affecting how disruptive his honest boredom was. "You've got nothing, engine's completely dry. Raise you, two questions, you're going to evade the first one anyway," he challenged. It would have been more obvious to try to fight the fangy smirk.