If she asked, Jack already had his explanation ready to go: they just got grabbed from any point in time. So what was a day for her was really ten days for him. But he was the same Jack Harkness she knew and loved -- sans the two thousand years he spent buried beneath Cardiff.
Jack plucked the note from her hands and crumpled it, shoving it into his pocket. "It's a duplicate," Jack said quickly. "And he also doesn't know how to spell it either. I-A-N-T-O," Jack intoned. "It's the one Gambit mistakenly had for a time," Jack said, shaking his head. There was a hint of a smile, though, knowing the Doctor had probably talked to Gambit to get it back.
He grinned at that, settling down on a step and patting the ground beside him. "I have someone you should meet. That very Welshman. He's the one who brews it for me."