Josh Groban Jokes David Foster, Who Just Turned 75, 'Didn't Have Any Gray Hair When I Met Him' (Exclusive)

Groban previously referred to his creative partnership with Foster as akin to a "musical married couple"

Legendary producer and songwriter David Foster is not exempt from some good old-fashioned ribbing, especially from Josh Groban.

Groban, who previously referred to his relationship with Foster as a "musical married couple" in a PEOPLE interview, reflected fondly on the pair's creative harmony. On the red carpet celebrating Foster's 75th birthday at the Hollywood Bowl on Sunday, PEOPLE caught up with Groban to ask about aging alongside the esteemed composer.

"He didn't have any gray hair when I first met him," Groban, 43, joked at the show, produced by Live Nation-Hewitt Silva. "Neither did I, for that matter!" Foster discovered Groban and his distinct voice when he was 16 and cut his teeth as a rehearsal singer, including as a stand-in for Andrea Bocelli.

"It's an amazing milestone, and he now has such an extraordinary body of work that he can celebrate and so many countless artists who owe their place on the stage to his ear and to his giving us a chance and a door to walk through," the "You Raise Me Up" singer continued.

Related: Katharine McPhee, 40, and David Foster, 75, Aren't 'Fighting' Age as They Celebrate Milestone Birthdays (Exclusive)

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If Groban is fighting off the gray hairs, not for long. The singer also revealed to PEOPLE that he's a new dog dad and the new addition to his family is taking up his time.

"His name is George. He's a West Highland Terrier, and he's very, very cute," Groban said. In 2020 Groban said goodbye to his beloved dog, Sweeney, whom he adopted in 2004.

He previously shared a snap of George on Instagram, and it looks like the new pup has discovered a love for stealing socks.

Related: Pia Toscano Hints David Foster and Katharine McPhee Might Sing at Her Wedding (Exclusive)

As for Katharine McPhee, 40, she reflected fondly on watching her husband Foster grow old with her. "It's a big number. It's exciting," McPhee told PEOPLE.

"I welcomed my 40s, and David didn't have any conversations about, like, 'Oh, I can't believe I'm 75,' or I didn't say, like, 'Oh, I can't believe I'm 40. I'm really mourning that.'" she noted, saying they were "cut from the same cloth."

Foster's Hollywood Bowl birthday celebration featured Kristin Chenoweth, Josh Groban, Andrea Bocelli, Michael Bublé, Jennifer Hudson and more paying tribute to his legacy. The producer said the event "sort of feels like my funeral while I’m alive."