The war in Iraq has stopped being a issue ever since around October, when good news started drifting out of Iraq and news stories could no longer deny that the surge was working and Iraq was stabalizing, people stopped caring about it.
One thing I am surprised about that poll is that usually Illegal Immigration takes a first or second place vote as the most important issue, up there with the economy. I guess South Carolina is far enough away from the border not to be truely effected by it.