"I love it when people revisit you in your dreams," McCartney said Monday before the music legend described how he dreams about being in a band again with Lennon.
"I'm often with John just talking about doing something and I come to get my bass ready to play and it's covered in sticky tape," the music legend continued. "I had a lot of dreams about John and they're always good."
Earlier in the program, Colbert presented McCartney with an old candid photo of himself laughing next to Lennon. McCartney said the photo reminded him that he was friends with Lennon after the Beatles broke up.
"It's a beautiful photo for me because it just reminds me of us working together and how cool it was," McCartney said.
Lennon was fatally shot by a deranged fan in New York in December 19080 when he was 40 years old.
McCartney also promoted on The Late Show his recently released children's book titled Hey Grandude! The book, inspired by McCartney's grandchildren, follows a grandpa going on adventures with his grandchildren.
"If people like it and people want it, I'm sure I can think of some more," McCartney said previously about penning more Grandude stories.