Harry was having a hard time not doing his 'happy Quidditch dance', given the wholesale slaughter of Slytherin on the field on Saturday. It had been a truly glorious moment for Gryffindor, and he'd been gratified to see most of Ravenclaw wielding some sort of red or gold.
Take that, Malfoy...
He was sitting in the stands reliving the victory when he spotted Wood - he waited till Hooch was gone (most likely cannoodling with Sprout in the greenhouse but Harry didn't want to go there) and jumped down. "Wood, mate," he greeted him. "Did you see that game?"