Fillion, who plays the title character on the hit show, didn't go to work last Friday because he is fighting with ABC about a four-day work week, the report said.
He returned as scheduled Tuesday and production resumed.
E! said the network and the show's producers want to keep Fillion happy, but find it difficult to shorten his work week since he is in almost every scene.
Celebrity Families of 2014 [PHOTOS]