More Polling IA-01 Whalen Momentum?

Missed this last week but Zogby poll taken 9/25 to 10/2 completely flip-flops all the other poll data in the Whalen-Braley Race, marking it 47 - 34 for Whalen. That's totally at odds with the previous polls I posted on here and here.

Starting in late August a RT Strategies poll had the race as Braley 54 - 41 Whalen. Then on September 9-13, Selzer and Co for the Des Moines Register had Braley 44 - 37 Whalen.

Looks like the negative ads are working on Bruce. Or that polling in Iowa is whacked. Or both.