Sean Penn and Charlize Theron
01/06/2014 AT 04:30 PM EST
After returning from a New Year's vacation to Hawaii
, Charlize Theron
and Sean Penn
spent the weekend together.
Back in L.A., Theron, 38, and Penn, 53, were spotted making a Starbucks run together on Saturday. While Theron picked up coffee, Penn waited for her in the car.
"They both were smiling," a witness tells PEOPLE, adding that Penn seemed "very happy and relaxed."
After driving to Theron's house, the Oscar winners emerged the next day for a trip to the movies, catching The Wolf of Wall Street
on Sunday night at the ArcLight Hollywood.
Reps haven't commented on the relationship, but there's been chemistry between the longtime friends before. According to a source, the duo were "touchy-feely" at Seth MacFarlane's Halloween party last October. Then, over New Year's, Theron joined Penn at his beachfront home on Oahu, and they flew back to L.A. together.
Theron, who is mom to 2-year-old Jackson, has been single since splitting with her longtime boyfriend Stuart Townsend
in 2010. Penn, famously wed
to Madonna in the '80s and Robin Wright in the '90s (they divorced in 2010
) has been linked to Petra Nemcova and Scarlett Johansson