How the Hulk goes about saving Bruce's life is something he's still afraid of. What's going to happen when his body gives out? Because he doesn't think the Hulk's aging. That's not something he wants to worry about now, so he lets Tony make him laugh, and he gives him a quick kiss.

"I might argue with that." He smiles warmly and a touch shyly at Tony before he backs away, letting him out of his embrace. "But a change of topic is good. We need to take care of this cat before it eats our living room. Or, you know, us."

Smiling still, he brushes past Tony to finish bringing their new pet its water dish.