updated 06/06/2011 AT 7:00 AM ET
•originally published 06/06/2011 AT 10:30 AM ET
Their reps say the two actors are “just friends,” but they appeared to be pretty close friends while shooting Playing the Field in Shreveport, La., last month. And over the weekend, new photos surfaced of Biel enjoying a ride on the back of Butler’s motorcycle down the PCH in Malibu.
A source in Shreveport tells PEOPLE that, off the set, Butler and Biel were “friendly but professional,” but it’s clear the two enjoyed each other’s company in their downtime, as well.