CNN

Biden occasionally slips off-message.

GAINESVILLE, Florida (CNN) – If you listen carefully, every so often Joe Biden will slip a few words into his speech not intended for those he’s giving the speech to.

“Stop moving the prompter.”

He’s talking about the two glass panels on either side of his podium - the teleprompter with his speech scrolling down that - controlled by Biden’s speechwriter and an assistant.

Typically, he can slip the line in without his supporters noticing - but Sunday, afternoon when the crowd laughed, Biden revealed the goal isn’t just to help him remember his remarks, but to keep him on message.

“I believe the possibilities for this country are absolutely amazing, and stop moving the prompter,” Biden told a laughing crowd of over 4,000 on the University of Florida campus. “There’s a prompter I hardly ever read here. They don’t want you to know that. They put it up to make me sound disciplined.”

Discipline is exactly what the Obama campaign would like of Biden - a man prone to long-windedness and frank comments during his vice preidential run that have occasionally been off-message.

“Rhetorical flourishes,” Barack Obama called Biden’s guarantee to donors at fundraiser in Seattle that Obama would face an international crisis in his first six months in office. Was it modesty when he told a voter in New Hampshire that Hillary Clinton may have been a better pick for VP?

The Delaware senator has a teleprompter at every speech and in recent weeks seems to have been reading it very carefully, staying close to the script and reducing the number of colorful Biden moments.

The combination of his newfound restraint and a lack of press conferences with the traveling press for almost two months led many in the press to accuse him of being 'muzzled.' (Biden took questions from his traveling press corps on Friday night for the first time in over seven weeks, and denied he'd been told to hold back.)

But then something will catch his eye.

“Now look, folks,” Biden said Thursday, intending to launch into a criticism of John McCain. “Hey, I didn’t even see the band up there. Hey, folks, how you guys doing? Thanks for being here. That’s really nice of you. Thank you. Um, that’s what you call getting off-message. But I tell ya, you guys look good.”

“The stakes by the way, the stakes [in this election] could not be higher,” he said later that day. “You all know, you students here…and by the way, I love your mascot, I call it a donkey you call it a mule, I like the look of it. You know what I mean? It’s a mule, I know a mule. And man, does it have a lot of kick.”

For reporters who have been listening to Biden's stump speeches several times a day for months, the next undisciplined moment is eagerly awaited.