I don't buy into the "weekend poll" argument, but the hurricane in Texas and especially yesterday's financial news is probably giving Obama a slight temporary boost. And this is just registered voters, which in Gallup polls tend to be about 4 points more favorable to the Democrats than a likely voter sample (according to Gallup itself).
Karl Rove does and said as much a week ago on FNC. He cited "technical reasons" why Dems poll better on the weekend but did not explain.
Weekend polls favor democrats. Republicans are just not home during the weekends. This is a fact known by almost every single pollster and pol in the business.