Obama brought this upon himself by hiding the true details of his past. I mean, besides the obvious details he had to admit such as the fact that he is an America-hating, freedom-hating, Christian-hating, capitalism-hating, whitey-hating, abortionist, statist, racist, Marxist pig.
Do you actually think he cares?
Judging by his actions, it seems that, far from being worried about it, he finds the birther movement mildly amusing.