Wow. Just, wow.
To me, it's not so much that she broke the law. She may very well have been ignorant of it (though ignorance is no excuse).
It's the cavalier attitude of the elections official and Robert Gibbs. ""You kind of have to drop the standard for the first lady, right?"
Uh, no.
You don't have to throw her in Leavenworth, but I think at the minimum an admonishment not to do it again might be in order. You could at least pretend we're still a nation of laws.