Alex Greenwald and Jacques Brautbar of Phantom Planet had a verbal exchange Saturday that will probably resonate through the ages.

“How many college kids can you fit into at Olsson’s?”

“This many!”

Exactly one day after the band appeared on “Late Night with David Letterman,” Phantom Planet took the stage at Olsson’s, a small book and music store located near Dupont Circle, to promote its new album. Most of the attendees were college age, but younger and older fans also packed into the place, cramming against CD racks and bookshelves to vie for a good spot.

And then, Phantom Planet started to rock. The five band members appeared to be almost as crowded on the tiny stage as the audience was on the floor, but that was a non-issue. They played loud and they played well, storming through a set consisting mostly of songs from Phantom Planet, their third full-length disc.

Greenwald, the group’s front man, was at his best – charismatic, energetic and expressive. His trademark expressions were in full force, including the overly literal hand motions, but fortunately this odd tendency did not detract from the performance. Guitarist Darren Robinson and bassist Sam Farrar rocked solidly up front, and guitarist Brautbar jittered around at breakneck speed, his mod haircut flouncing all over the place. Jeff Conrad, the band’s new drummer, also gave an impressive performance. He provided a solid and dynamic backbeat that propelled the music forward with thoroughly reckless abandon. Phantom Planet has always been a good live band, but somehow its new material sounded better than ever. Maybe this is because Phantom Planet is a lo-fi-sounding rocker of an album, a complete turnaround from its pop-oriented predecessors, Phantom Planet is Missing and The Guest. Each song sounded so good that it seemed like the entire album was meant to be played live.

In between songs, Greenwald thanked everyone who bought the new album, as well as those who bought the band’s previous releases.

“I mean, really,” he told the crowd. “Thank you.”

Finally the band played its convulsive first single, “Big Brat,” and then, suddenly, the guys were off the stage. They spent the next hour or so signing CD covers for a massive line of people – nearly everyone who watched the show stuck around. So it was over, and Greenwald hadn’t even crowd-surfed like he usually does at Phantom Planet shows. But maybe this was a good thing, considering all the bookshelves.