I see this a lot, too.  The New York Times does a feature on it.  The article starts with a look at Jon Downs, a liberal Democrat in New Hope, PA., who constantly checks his computer for latest polls.

“Look, I have this sense of impending doom; we’ve had a couple of elections stolen already,” Mr. Downs said. “The only thing worse than losing is to think that you’re going to win and then lose.”
He considers that prospect and mutters, almost involuntarily, “Oh, God.”

To talk with left-leaning Democrats in New Hope, San Francisco or Miami Beach, to drill deep into their id, is to stand at the intersection of Liberal and High Anxiety.

Right now, more than a few are having a these-polls-are-too-good-to-be-true, we-still-could-lose-this-election moment. Their consuming and possibly over-caffeinated worry is that their prayers and nightly phone calls to undecided voters in Toledo, Ohio, notwithstanding, Mr. Obama might fall short on Election Day.

To walk on Broadway, on the Upper West Side of Manhattan, is to feel their pain. “Oh, God, I’m optimistic, but I can’t look at the polls,” said Patricia Kuhlman, 54, nervously tapping her Obama/Biden ’08 button. “I’m a PBS/NPR kind of person, and, O.K., I do look at some polls.”

Ms. Kuhlman shakes her head and says, “If he doesn’t get this, I’ll be crying so hard.”

A young woman, Shana Rosen, walks by. She is from Denver and said she had told her boyfriend that their love life was on hold while she sweated out Mr. Obama’s performance in Colorado. Ask Lucy Slurzberg, an Upper West Side psychotherapist, how many of her liberal patients speak of their electoral fears during their sessions, and she answers: “Oh, only about 90 percent of them.”

Listen….