Hagan has made courting women voters, especially single women, the backbone of her campaign -- "heels on the ground" was what she called it -- and it shows, with a 49-33 edge among women, similar to what other polls have shown.
A four-point lead isn't much given the dynamics of the race--sixth year election vulnerable incumbent, pink/purple state, very unpopular Democrat in White House, older and whiter electorate. I'll buy the notion that CO, NC, and IA all tilt to the Democrat right now. But I just don't buy the idea that they'll likely stay that way in a year like this.
The Republican Party brand is also deeply unpopular nationally and while that may not matter much in solid Republican states, the swing states are a different story. There is a reason why the races in Colorado, North Carolina and Iowa are trending in Democrats favor. Gardner, Tillis and Ernst have records which are an ill fit for running in purple states. Now that voters are being informed of those records they are not doing so well.