Plopsy

Hi all, I was wondering how common it is to be expected to work during the winter break? I work as a research assistant for a professor and he is expecting his 5 RA's to work during the winter break. 4 of us are PhD students and one is a master's student. At the previous institution I was at it was clearly stated by the graduate school that you worked from the time classes began until the last day of finals week and that was the end of your responsibilities. At the place I am at now, there seems to be no policy in place about when graduate assistants work and don't work. So I am basically wondering how common it is to be expected to work during the winter break? None of the other RAs in the department are working or are expected to that I have talked with. I think its a major league douche move on the professors part. Any thoughts? Thanks