It was against Schalke and I think the incident you are talking about is after the final whistle when he celebrated right in front of Christian Poulsen. But there was more to it; Poulsen had performed a 'cynical' man-marking job on Kaka in both matches and the Danish midfielders in renown as one of the dirtiest players in Europe. Any remember Euro 2004 with Totti?
Anyway I don't consider Gattuso annoying as he is a team-player but very modest and controlled off the pitch.