I don't think that i have ever seen that. But yes that would be a real good guess. the unit is called a duplexer. and thats exactly what it should be doing is pulling the paper out and flipping it over so it can print on the other side.
It just seems strange that it can pull it out and put it back and not flip it over. Usually if they are going to screw up they will jam and not put it back at all.