Actually, his flipflopping is a little bit more than just that.
First, he voted on the war. Then, he came out against the war when it happened. Then, in a debate not long after Baghdad fell, he mentioned that he voted for the war. Then, as people kept dying, he focused on his dislike for the war. Finally, right after Saddam got caught, he came out and lambasted Dean for his dislike of the war, and then, while campaigning in Iowa, he again stated that he was against the war.