Jennifer Aniston back on the set of We're the Millers
08/14/2012 at 10:00 AM EDT
is back to filming We're the Millers
after accepting a different sort of role last Friday – as fiancée to Justin Theroux
Aniston, 43, was spotted reporting to the comedy's Wilmington, N.C., set in dark glasses and a fitted grey dress on Monday – her first appearance since Theroux's rep told PEOPLE of the engagement Sunday.
A source tells PEOPLE that Aniston returned to Wilmington late Sunday night (sans 41-year-old Theroux), and "she looked happy."
"Justin Theroux had an amazing birthday on Friday, receiving an extraordinary gift when his girlfriend, Jennifer Aniston, accepted his proposal of marriage," Theroux's rep told PEOPLE exclusively on Sunday about the pair, who starred together in 2012's Wanderlust
Theroux also spent time in North Carolina earlier this month, when he visited Aniston while she was taking a break from shooting We're the Millers
The film, due to open next year, will also star Emma Roberts
and Aniston's Horrible Bosses costar Jason Sudeikis
Reporting by MICHAELE BALLARD