Probably a Sandy-effect, but there are some straws in the psephological wind to back it up:
A Zogby poll finds Obama has picked up five points among independents, perhaps because of how he has handled the federal response to Hurricane Sandy. Meanwhile the latest national Public Policy Polling tracking poll shows Obama turning a longtime disadvantage with independents into a 49% to 44% advantage. Furthermore, a new national ABC News/Washington Post tracking poll shows Obama and Romney deadlocked with independents, at 46% each, matching Obama's best showing among that group in that survey and coming after Romney had reached a high of 58% just a week and a half earlier.
Finally, the Politico/GWU tracking poll finds the two men essentially tied with independents just a week after Romney held a double-digit lead with them.
(Chart: the national race right now since October 1, sans Rasmussen, from Pollster)