It's not just because it's smart politics (as soon as the apology is accepted, the story dies and the MSM moves on).
It's not just because it's the gracious thing to do (although it is).
It's because Michele Bachmann is too talented a politician and too smart a woman to start getting caught in petty games with the press. Every truly good candidate convinces voters that the campaign isn't about HIM (or her); it's about America. Grudge-holding over a personal insult (in the form of an admittedly outrageous question from the media) doesn't fit that narrative.
Finally, rightly or wrongly, women are frequently stereotyped as less tough than men, and taking things more "personally." What a shame if a remarkably bright and accomplished woman -- one whose performance in the race thus far should make other female Republicans proud -- allowed herself to play into that stereotype.
Let bygones be bygones. Michele Bachmann -- and most importantly, the principles she stands for -- are bigger than some silly question on a Sunday morning chat show, especially when the host has at least had the good grace to apologize.