In preview clips from an interview Sunday with "60 Minutes," Leno said he's not quite ready to retire.
"It's not my decision," he said.
"I think I probably would have stayed if we didn't have an extremely qualified, young guy ready to jump in," he added, referring to Jimmy Fallon, who's taking over the hosting duties Feb. 17 after the Winter Olympics.
Leno praised Fallon, calling him "more like Johnny [Carson] than anybody since."
Leno said he was "blindsided" by NBC executives when they asked him to leave the show the first time in 2009. Fellow late-night host Conan O'Brien briefly took the helm of "The Tonight Show" before he was pushed out and Leno returned to the show.
Leno said he never understood why he was cast as the bad guy in that situation, the Los Angeles Times reported.
"I didn't quite understand that, but I never chose to answer any of those things or make fun of any other people involved," Leno said. "It's not my way."