Really, he was trying not to laugh at her rant because he just hated Nascar that much. (His mother called it Nastycar. Apparently the hate was a family thing.) And he really wasn't going to argue with her so he just shook his head a little...
Back to the startled though. Because Jamie was never called cute or adorable. "Er... Yeah. Totally new. It was kind of like 'Oh crap, screwed up. Must make him happy. How do I do this? He's so cute when he pouts...'"