David Foster and Katharine McPhee Stroll Arm-in-Arm as Source Says They're 'Dear Friends, Nothing More'

In September, an insider denied that David Foster and Katharine McPhee have a romantic relationship, telling PEOPLE the pair are only "colleagues, collaborators and longtime friends"

David Foster and Katharine McPhee were photographed walking arm-in-arm in Brentwood, California, over the weekend — a month after multiple sources told PEOPLE the “colleagues, collaborators and longtime friends” are not dating.

During the outing, Foster and McPhee, 33, were also spotted at an ATM, where the latter placed her hand on the 67-year-old’s behind.

However, a source close to the couple tells PEOPLE that the platonic pair are merely having “some fun” at the expense of photographers.

“Katharine and David are in no way romantically involved,” says the source. “They are dear, old friends who genuinely love spending time together, but it is nothing more than that. They are also, however, both savvy enough to see quite obvious paparazzi stalking them, and they know how to have some fun with them.”

X17

Last month, Foster’s daughter Erin shared photos of her dad and McPhee at the Grammy Museum’s third annual gala at The Novo in Los Angeles, writing in the caption, “Excited about my new step mom.”

A source close to the situation told PEOPLE at the time that the social media posts were a joke.

“This is not at all true,” the source said of the dating rumors. “Erin’s quite obviously tongue-in-cheek and sarcastic Instagram comments were pointed at those who can’t seem to grasp that her dad and Kat can be colleagues, collaborators and longtime friends without it being some big romance. They can’t even perform together without people saying they’re headed down the aisle. Erin was messing with people who jump to conclusions.”

A Foster source reiterated, “They are absolutely not dating.”

McPhee has previously collaborated with the 67-year-old Grammy-winning producer for a few live performances (including his 2008 PBS tribute concert Hit Man: David Foster & Friends).

RELATED VIDEO: Katharine McPhee Performs Her New Single ‘Lick My Lips’

At the September Grammy event, McPhee spoke about how much Foster means to her.

“He’s an incredible friend and I just pinch myself when I get to spend time with him on a personal level,” the “Lick My Lips” singer told Entertainment Tonight — while wearing a low-cut, asymmetrical black dress. “I love his outlook on life and how he treats people. He’s a really a special person in my life.”

“What I’ve learned from him is how lucky we are to do what we do,” she added. “He’s always reminding me and it’s comforting to know that it’s possible to walk through this life he’s had — working with incredible people, being friends with ex-presidents and world leaders — and still have that perspective. He’s so well-connected, but still just a simple guy from Canada with his little Canadian accent!”