One reason I think that scene was done to show us that Ryan knows Kelly very very well. He'd probably be able to tell you how long she'd talk about any subject. Of course in his expression there was "sweet, she's winning me money," but it most definitely had "that's my girl" written all over it, too. He was proud of her for coming threw for him.

But I also think Ryan can't help being amused by Kelly's enthusiasm about certain things. He smiled to the camera in a deleted scene for Women's Appreciation after Kelly got excited about going to the mall.

Ryan thinks Kelly is cute in those types of moments.

Great story!