A long, long time ago, in the distant political era of 2013, Paul Shaffer was bandleader for “Late Show With David Letterman” and heard of the Roots playing an instrumental version of a profane Fishbone song to introduce then-U.S. Rep. Michele Bachmann on “The Tonight Show Starring Jimmy Fallon.”

Later, Shaffer dropped in a snippet of the same song as part of a Top 10 list involving the tea party leader. “The difference was, I didn’t tweet it,” Shaffer recalls. “Because you know what? Nobody recognized it or even commented at all. It went by. That’s sort of a generational difference.

“(Roots drummer) Questlove, of course, is all about the tweet, and I have nothing but the utmost respect for a man who is an incredible drummer,” adds Shaffer, 67, the bandleader who left late-night TV when Letterman retired in 2015. “My thing was to lay these things in, and you can get away with a little more stuff. Questlove was like the criminal who tweets, ‘I just robbed a bank LOL,’ and wonders why the feds can find him.”

After “Late Show” ended, Shaffer, the bald, wry, erudite Canadian who punctuated Letterman’s jokes with sub-Ed McMahon cackles for 33 years, had little to do. He told Newsweek he planned to learn to sight-read music, play the Hammond organ bass pedals and do some acting. He has practiced the pedals, somewhat, but ran out of time for the other endeavors when he decided to make an album, “Paul Shaffer & The World’s Most Dangerous Band,” earlier this year, and go on tour with his “Late Show” colleagues.

“There is a school of thought that says, ‘You’re not really an organ player unless you’re playing the pedals’ — that’s why it is super-important to me,” the longtime keyboardist says, by phone from Manhattan. “Acting, though, no one has come up with the right three-episode arc in ‘Hawaii Five-O’ or ‘New Girl.’ Not yet. And I can absolutely read music on score paper, but sight-reading is another skill altogether, and that is just a question of putting in the time. I thought I was going to have more time than I do.”

For the band’s recent album, Shaffer cedes most of the songs to stars such as Rilo Kiley’s Jenny Lewis, country singer Darius Rucker, rock legend Dion and, in a bizarre lounge-music skit, comedian and “Late Show” favorite Bill Murray.

“I sort of transformed into a frontman. I had no other choice,” Shaffer says. “Such a difference between being a guy’s sidekick for 33 years and fronting the organization. But I’m having an absolute gas and finding that it is an art form unto itself, and every time I do it, I learn more.”

Shaffer still meets with the now-big-bearded Letterman every few weeks. (He calls himself “the conduit” between the reclusive comedy star and the Rock and Roll Hall of Fame, for which Letterman inducted Pearl Jam in a memorable April speech.) “We worked pretty hard for those 33 years, and from the two times that I got to host (the show), I couldn’t believe the difference. ‘Oh my goodness, this is what he’s been doing every night,’?” Shaffer says. “A person doesn’t have to work that hard forever.”

Steve Knopper is a freelance writer.