So given a discrepancy between the actual votes, and the exit polls you're believing the exit polls? Even though we know that since the 1980's more people have refused to answer such questions (I will not), and that we have demonstrable proof that people will often lie and take the more PC position in public when they voted the other way in private.
Really, if they could have (and I think they can) changed the vote, they were more interested in changing it on Prop 8, but let the vote for Obama go through? Somehow you're going to have to convince me that a ballot issue, that everyone knows, regardless of the outcome, was going to come up again, and again, and again, was more important than the election of the President? Sorry, that does not compute.