The veteran, who has been missing this season due to a serious eye complaint, was a late substitute for the 2-0 win.
"It was the end of a nightmare that lasted six months. It's all over now," Gattuso told Radio Deejay.
"For four months we worked to treat a condition that then proved to be something else entirely. Now with all the cortisone they've been giving me, I've been pumped up like a boxer!"