Interviewers are rarely fed questions, they're fed topics to either discuss or avoid. Like Obama going into any interview, the interviewer was given what Obama wanted to talk about, like Healthcare, or whatever news topic of the day. They were probably also given things not to talk about, like birth certificates, or things like that. shows like 60 Minutes are issue oriented shows, you go on to discuss the issue of the day, so often any random side questions would be strongly discouraged.