Don't worry, he hasn't taken up any steamy offers from Paris Hilton or Kim Kardashian.

But an unexpected, older woman joined Justin Timberlake at Wednesday's Hollywood premiere of his new movie Alpha Dog. His mom, Lynn Harless.

It was a sweet gesture, but was it also a sign that there's trouble with long-time girlfriend, Cameron Diaz? We hope not, as the actress and JT are one of The Hollywood Gossip's favorite famous couples.

After the movie, mother and hot son hit the afterparty at Ivar Studios.

He and Harless hung out in the venue's VIP section, chatting and taking photos with his Alpha Dog costars until just before 11 p.m., when they headed out to the club Social Hollywood.

There, they met up with Scarlett Johansson, who recently filmed a video for one of Timberlake's new songs. She shared a one-on-one with him for about an hour before Harless joined in the conversation â€" and then hit the dance floor with her son to the Jackson 5's "ABC."

Later, while Timberlake hung out with some of his Alpha Dog costars, including Emile Hirsch, Shawn Hatosy, Ben Foster and Olivia Wilde, Harless and Johansson talked until the club closed.

Sounds like Dina Lohan could learn a lesson or two from Harless about how to behave in public.