There it was. That little hint doubt where Tony started to think he was telling the truth.

Gladio... could have dragged it on. Was even tempted. But the look in Tony's eyes was enough to let him know that he could go too far with this. So, with a heavy sigh, Gladio let his shovel drop against the wall and walked over to his friend. He lifted his hands and dropped them onto Tony's shoulders...

"... I'm joking." And now he grinned, laughter in his voice. "Had you for a second there though."