DETROIT—The annual Netroots Nation conference, a grassroots gathering of progressive activists from LGBT to labor unions to Ready for Hillary, was a little ignored by the media last year. I distinctly remember sitting in a row of media desks during the keynote speeches by Barney Frank and Howard Dean, and seeing empty chairs outnumber the bodies of reporters by 2-to-1.

There was no Narrative that year. There is now—Sen. Elizabeth Warren, who began the week with a rally for the Democrats' Senate candidate in West Virginia, is closing it with a Netroots Nation speech and a rally for Senate candidate Gary Peters. Michigan is safer and bluer than the Mountain State, obviously, and Peters has started to build a lead, but the opportunity to ask progressive activists if they are Ready for President Warren is just too rich. The media presence at the Peters rally is as big as the media presence for the entire Netroots keynote last year.

As a skeptic of Warrenmentum (polling, reality suggest progressives are generally solid behind Hillary 2016), I finally found a reason that's keeping speculation hot. Voters assume Warren is much younger than Clinton.

"I wish Hillary would have won last time," said Irma Glaser, a 77-year-old retiree perched at the front of the stage where Warren would speak. Glaser was so pro-Clinton, actually, that she put Claire McCaskill on her "list" for daring to endorse a male candidate over the first credible female president-to-be. "But the Republicans are going to push on her age. It's been eight years, and who knows what's going to happen by 2016?"

Glaser wanted Warren to run for that reason—she's "younger." How much younger? "I don't know, but I'd guess 15 years, 20 years," said Glaser.

Other voters guesstimated that Warren was around a decade younger than Clinton. She's actually only 18 months younger, born in 1949, 12 years before the current president of the United States, and four years before the current dynastic hope of the GOP, Jeb Bush. But she just got elected in 2012, so people don't assume she's around the same age as the woman who became Arkansas' first lady in 1979.