The British actor, whose ex-girlfriend, Kristen Stewart, visited him at his home in Beverly Hills for three hours last week, and the 22-year-old model, whose parents are Sean Penn and Robin Wright, were spotted at the launch of Angie Banicki's new book, '30 Before 30' at the Roosevelt Hotel in Los Angeles last Wednesday night.
An eyewitness said the duo, who were first linked in September, were joined by two other people and spent much of the evening together, but left the event separately at the same time.
The source also told E! News that the 27-year-old 'Twilight Saga' star attracted a lot of attention at the party, saying: "Girls were flirting with him."
Another source recently claimed that Robert and Dylan's relationship isn't serious yet.
However, friends have poured cold water on speculation the 'Water For Elephants' star misses Kristen, 23, and wants to get back together with her.
One friend said that while "there was lots of animosity after the split," the former couple have "moved on and gradually gotten over it."
The insider added: "They are cordial now. They will not get back together."
Robert and Kristen ended their four-year relationship in May after they struggled to get past the actress's "momentary indiscretion" with her 'Snow White and the Huntsman' director Rupert Sanders in July 2012.