Between the alcohol and the familiarity of the situation, Groot doesn't even realize just how relieved he is to see Rocket. He puts the bottle down and tucks his arms in awkwardly, looking some combination of annoyed and humiliated. "I am GroooOOOOT," he half-grumbles, half-whines, doing his best to shrink into the background.

And then he realizes that he's more happy than he is embarrassed.

He tries not to smile at dad. Now that would be embarrassing.