Steve Marmel understandably flipped out when he saw photos of President Obama continuing his Hawaii vacation amid terror troubles. He let loose in the broadly liberal Huffington Post, chiding a president whom he otherwise supports:

That vacation should have been over moments after the plane landed at noon on Christmas day ... This is no "My Pet Goat," or sharing birthday cake with John McCain while New Orleans flooded. But it's close enough that it's making the hairs on the back of my neck stand up... and I like this president.
But now Marmel has backtracked. After reading a first-hand account from a passenger on NW Flight 253 in the Huffington Post, he did what few commentators are willing to do: he withdrew his opinion.
By starting this discussion with incorrect information, I believe it muddies the piece as a whole. The first piece I wrote here was this: "When Wrong, We Need to Own up to It." Owning.
Marmel followed this up with even more elaboration, after commenters accused him of being "coerced" into a retraction. But what compelled the change was the fact that the photo was taken in 2008, and Marmel believes that "if I write an opinion piece based on a fact, and that fact is incorrect, then it's my responsibility to deal with that."