Why did Michelle obama say "Give me more white people"?

As I recall this happened prior to a speaking engagement for Senator Obama. I was watching Fox the day she made this statement, must have been a couple of weeks ago. I can understand her saying this but could'nt believe there was an open mic. Probably a Clinton infiltrator. LOL The reason for her saying this was nothing more than to make it look as though Obama has a large following of white support for his campaign.