The duo, who have maintained they’re simply good friends, stepped out together in West Hollywood on Monday for a night on the town.
The 33-year-old American Idol alum donned a chic all-black ensemble, including leather pants and a cozy long sweater, for the outing, accessorizing with brown booties and a white purse. Foster, 68, sported blue jeans with a black blazer over a button-down shirt.
It’s the second hang-out in as many days for the duo, having attended Sunday’s game between the Los Angeles Lakers and the Memphis Grizzlies together.
“They seemed to be having a fun,” an eyewitness told E! News. “They were chatting with the people in the seats next to them….Didn’t see them kiss or hold hands but certainly seemed like they were into each other and the game.”
RELATED VIDEO: David Foster’s Daughter Calls Katharine McPhee “Amazing” After Pair Spotted Walking Arm-in-Arm
Rumors about David and McPhee’s relationship started in September after “The Best of Me” singer’s daughter Erin Foster shared photos of the pair 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.”
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).
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 Smash actress told Entertainment Tonight. “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!”
Last month, the two were photographed walking arm-in-arm in Brentwood, California. A source told PEOPLE at the time, though, that the pair are platonic and were merely having “some fun” at the expense of photographers.
“It’s quite obvious by my track record that I love being married, so I wouldn’t say no to being married again,” Foster tells PEOPLE exclusively. “I like the concept, I’m just not that good at it.”