It's called playing to the audience. It's what politicians do good ones, anyway. Obama is nothing if not a politician, and he comes with all the baggage that the label implies. Both he and his campaign would do well to make sure he sticks to the facts in the future, because he might cross the line in a way that will discredit him if he's not careful.
And Andy Martin will be there to report every misstep he makes and even some he doesn't.