Though Billy Joel is now happily remarried, the singer still has a thing or two to say about his ex-wife Christie Brinkley‘s love life!

During his NYC concert on Saturday, Sept. 26, the 66-year-old star jokingly griped onstage about Christie’s new relationship with John Mellencamp, 63.

“And now she’s dating John Mellencamp,” Billy — who recently welcomed his second child, daughter Della Rose, with wife Alexis Roderick — quipped after performing his hit, “The Longest Time,” a song written about Christie.

christie brinkley and john mellencamp

New couple Christie (left) and John (right). (Photo Credits: Getty Images)

The former supermodel, 61, and John were first spotted out together in NYC on Sept. 14. “[Christie has] been a bit shy about putting herself back out there, [but] with John, there’s comfort. He’s more like an old friend and a member of the extended family,” a source close to the couple told Closer Weekly of their new romance.

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“It’s too early to tell what might develop,” the insider added. “But so far, Christie’s certainly put a smile on John’s face!”

christie brinkley and billy joel

Christie and Billy in March 1999.

Christie has been married four times; to French artist Jean-François Allaux from 1973 to 1981, to Billy from 1985 until 1994, to real estate developer Richard Taubman from 1994 to 1995 and to architect Peter Halsey Cook from 1996 until 2008. She is mom to a 29-year-old daughter, Alexa Ray, with Billy, a son, Jack, 20, with Richard and a 17-year-old daughter, Sailor, with Peter.

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John was married to Priscilla Esterline from 1970 until 1981, to Victoria Granucci from 1981 to 1989 and to former model Elaine Irwin from 1992 until 2010. Following his most recent divorce, the “Jack & Diane” singer began dating actress Meg Ryan in 2011 but they split in 2015.