Why did McCain Sit next to Palin when she Interviewed with Couric the Second time?

Palin only did about 4 interview's during the entire 2008 campaign process. She did many speaking events though, I think she had more rally's than Biden for sure. But why was McCain so Insecure about allowing her to do her own thing? Even when he was sitting next to her in the Couric #2 Interview McCain looked Fidgety. Like he was a Parent sitting in on a Teacher student Conference.