CBM
"Stark has set Banner up to be able to continue his good works in Stark Tower, and Tony has a project of his own," Robert Downey Jr. told Entertainent Weekly during a video interview at Comic-Con. "So, it's one of those things where it's like your second development team 'Hey, how is it going over there, that looks really nice and green; can I talk to you about this other idea I have'.
Bet it's over the Hulk swiping schwarma from Tony.