Maybe the laugh through the filter of his mask didn't sound so bitter, and it was over quickly, Iron Man's shoulders drooping as he said, "Me, too." Despite the gnawing self-loathing in Tony's gut, this had gone surprisingly well so far, making him suspicious of his good fortune and all of Loki's warnings against bringing Thor into the fold. If this wasn't all part of some grand plan like Hammer claimed, then Loki was right; Thor's presence alone could break the whole system down, and he could be just what Tony needed. What happened in that office without him?
"Your teseract..." Iron Man invited, "It's not how you're traveling now, is it?" Maybe Tony would hang onto that while Thor informed Hammer where he could kiss and bring it to SE for safekeeping. Just in case, until Tony had the chance to figure out what it could do and lock out anything Hammer might get too excited over.