Jay Leno, right, and Billy Crystal appear during the final taping of NBC’s “The Tonight Show with Jay Leno.” (Matt Sayles/Invision/AP)

Conan O’Brien might still be a tad bitter about his “Tonight Show” debacle. So did you really think he would let Jay Leno’s last night hosting “The Tonight Show” go by without one dig?

“The Olympics start airing tonight on NBC. That’s right, NBC has the Olympics,” O’Brien started, innocently enough during his monologue Thursday night on his TBS late-night show. “It’s a big deal. NBC will finally get to show somebody who’s okay with passing the torch.”

(Starts around 2:20)

Ohhh. Big cheers from the crowd as Conan tried to hide his smirk that evolved into a very pleased grin. “I allowed myself one, but it was a good one,” he admitted, referring to that whole disaster a few years ago when Leno stepped back in to take over “The Tonight Show” after Conan lasted all of seven months.

Elsewhere in the late-night universe, as a tearful Leno bid goodbye over on NBC, his fellow late-night comedians held back. ABC’s Jimmy Kimmel, famously not a Leno fan, chose not to engage, though he booked an all-star line-up (George Clooney, Matt Damon, etc.) to air opposite Leno. However, Kimmel did tweet a seemingly sincere goodbye earlier in the day:

More surprising was the relatively tame CBS “Late Show’s” David Letterman, never one to miss taking a dig at his long-time nemesis. Not so much on Thursday. “Tonight is a big night for change in late-night television,” Letterman remarked near the top of the program. “Our friend Jay Leno, 22 years as host of ‘The Tonight Show’ — 22 years, that’s remarkable, isn’t it? — 22 years and tonight will be his last program.”

Letterman spent the next minute reading stats from a notecard: Leno started on “The Tonight Show” in 1992. (No mention how many thought Letterman himself was a shoo-in for the job.) Leno was also a guest on Letterman’s former “Late Night” more than 40 times.

That was pretty much it, save for Letterman bantering with band leader Paul Shaffer about how “our little buddy Jimmy Fallon” will be taking over for Leno on Feb. 17.

“Congratulations to a wonderful run,” Letterman concluded. “And I’ll tell you something — if I was Jay Leno and I was retiring, you know what I would do? I would go out and buy myself a car.”

Later at 12:35, “Tonight Show” replacement Fallon gave Leno a quick shout out on “Late Night.” On CBS’s “Late Late Show,” Craig Ferguson sent his own good wishes, calling it “a great day for my pal Jay Leno who’s finally free, congratulations.”

Ferguson joked that it was Leno’s last night — at least for a couple months. He wrapped it up with some words of wisdom.

“Remember kids at home,” Ferguson said. “If you work hard and you succeed and you get to the top — someday you’ll be fired.”