I looked at this poll and it has some very strange internals. They don't list the party breakdowns, but they show McCain tied among men, and only leading by 1 for voters over 50. It also shows no movement of women to McCain.
Unless we start seeing other polls with the same internals, I am pretty comfortable viewing this poll as an outlier, especially without further information on party identification distribution.
McCain down 4 in VA is no more believable than the other poll out today showing Obama up by only 5 in the State of New York.