Tom Petty and the Heartbreakers are as American as apple pie, piping out songs that had tens of thousands at Bonnaroo singing along into the hazy air at What Stage on Friday.

It was a strange move for the festival to headline Tom Petty and the Heartbreakers, but a lot of things about Bonnaroo this year were different. Two nights were headlined by bands that broke the jam-band stereotype.

Unexpected acts aside, most of the bands playing days at this year’s ’Roo owe a lot to Petty and the musical legacy he’s been building for the past thirty years. And if the hippies weren’t digging it, they certainly didn’t have to hang around and sing along.

“Can I jam for you?” Petty asks the swelling crowd. They roar back a yes. It’s 45 minutes late, after all.

It’s nostalgia in action. Most of Petty’s comments were indecipherable, but once he stopped talking we all new the words.

“Last Dance with Mary Jane” came early in the set, so did “You Don’t Know How it Feels.” They took a break from the classics to play a few tunes off of their forthcoming album, Highway Companions, their first release in three years, including the raspy, whiskey blues tune “Saving Grace.”

While the new material is smooth, after a day roasting under the Tennessee sun the energy level drooped. But the Heartbreakers still had a few tricks up their sleeves.

After another inarticulate introduction, the band started playing “Stop Draggin’ My Heart Around” and Stevie Nicks sails in for a few songs. If Petty’s age is showing, it only highlights how brilliant and consistent Nicks is. Her voice is eternally spot on, and her energy is contagious.

Nicks’ surprise visit breathed new life into the set, and the band swung back into the classics. The set started late and ended early, but everyone seemed satisfied to call it a night.

I guess that’s what he gets for pulling out the “Mary Jane” so early in the night.