Tony gladly snatched his hand back to hide his grin as he gave a horrified giggle at Steve's warning, making a mental note to really look into that. They hadn't exactly been careful, and who knew what kind of junk science was going on before Tony was gifted to this brilliant, blue ball? It wasn't as though Tony could spend too much time examining Steve and the serum, this was science, life- and death-altering at that, it was really worth a few hours on the table under Tony's scrutiny.
"Well, why didn't you say so?" Tony replied, as though Steve hadn't said several times, as he hopped easily to his feet, leaving Steve to grapple for his life alert on the floor. There was cake, now it was an occassion. What was Steve going to do with that if Tony had said 'no'? He certainly seemed anxious enough to begin with--wait, that was just Tony, wasn't it? Steve knew exactly how this was going to go, probably knew for days now, or, "How long were you planning this? Did Pepper know?" Of course he could keep his ring and his cake and his big damn grin to himself and know exactly what Tony was going to do all along.