Look at the internals. The south is oversampled. But the good news is, the only region Hillary is winning is the west and the margin is paper thin.
Is that oversampled? Texas, Florida combined vs NY, NJ, PA, et. al. The south has had pop growth and NE has not.
The real issue is the D/R/I mix. Was that imposed after the sample or was that the self identification?
I can't remember the last poll I saw where the three parties were split evenly. As much as I love this poll, I think it's off because of oversampling Republicans.