Credit: Alexander Tamargo/; Charles Eshelman/FilmMagic

Amanda Seyfried and Ryan Phillippe not only got cozy at Kate Hudson's annual Halloween bash at her Pacific Palisades, Calif., home -- they also got close at another bash, hosted by CAA's Todd Feldman on Saturday night in Beverly Hills.

Seyfried, 24, who wore a dog costume, was overheard telling partygoers, "We're hanging out. He told me this was a good party."

She was "flirty" all night, says a witness. "She was listening to him and talking close but no making out ... she seemed intrigued by him."

Phillippe, 36, dressed as Star Wars character Obi-Wan Kenobi, "was being extra friendly and spirited," adds the onlooker. "I've never seen him in such a good mood. He looked cute and was smiling a lot."

Says another insider, "They definitely hit it off."

On Sunday, Seyfried played coy when asked by x17 if they were an item. "You never know," she said while getting into her car.