So if you can physically shake the whole assembly by hand in all directions would this be a reason for needing to change them??
erm... thats sounds to me as if its extremely loose?!
in which case thats BAD!!! you shouldn't be able to shake it at all!
all im saying is that slight movement (from turning your wheels (the suspension twists with the wheel when they turn!)) and not sitting identical to each other is normal!
top mounts are cheap, about £8 each I think! so if your worried and can fit them yourself (you need to remove the suspension from the car to fit new top mounts!) then simply buy new ones for pease of mind!