Actually, Kelly, that is an example that happens often here on the board, if it didn't happen to everyone, then it does not happen, but that is not totally true. While I know of no-one who has been denied re-entry with over-stays, I do know of people who have been questioned at the border by immigration and then given less time, as few as 30 days for one friend.
In other words, chances are they will not care, but there is no promise of that. It boils down to the fact that is is very easy not to follow the law, and I am not judging because I had overstays before I had my carnet as well, and it was just easier to pay the fine...but if you break the law, there could be consequences and we are here at the discretion of the government.
That being said, I agree that there is very little to worry about, but not NOTHING to worry about.