It makes no difference. Not all ex post facto laws are unconstitutional—only those which take away rights.
I think Obama’s campaign is setting up issues like this and the Muslim thing in order to say “see, the GOP is swift boating me, they have no new ideas”.
Then when people FINALLY get to the real issues, his hard left policies that are neo-marxist he will just call it another smear and ignore it.
It is the little boy who cried wolf syndrome and the MSM will go right alone with it.