Obama pulling even with Hillary in Pennsylvania?

This poll, showing Obama pulling even with Hillary in Pennsylvania, cannot possibly be correct:

Pennsylvania Democrats

Mar 7-8 / Mar 26-27 / Apr 5-6

Clinton 52% / 51% / 45%

Obama 41% / 39% / 45%

Someone else 1% / 2% / 4%

Undecided 6% / 8% / 6%

While I think the Bosnia lie did significant damage to Hillary's campaign, and Obama wasn't hurt nearly as bad as was initially suspected on the Radical Reverend (thanks in large part to the candidate's widely-hailed race speech), I think this much of a swing is beyond credibility and this poll is likely an outlier. That said, even a single-digit loss in Pennsylvania would be a win for Obama, and he appears to be building up an avalanche of support in North Carolina.