if it is the mounts, it's not necessarily serious as there are a couple of things you can do that might sort it
check the tightness of all of the engine mount and subframe mounting nuts/bolts (especially the bottom nut on the upper gearbox mount); also, loosen the four top engine mount bolts and pull the engine forward before retightening - these two things are about all you can do before you start thinking about renewing the mounts. check it out on search as there are diagrams and some decent explanations of what to be doing