Hey mate, the Cush rubbers are easy to check. With the bike on its side stand, hold the top of the back wheel with your left hand then grab the sprocket with your right hand then give the sprocket a good wiggle to see if there is any play in it. If there is only a small amount of play then you could firm them up with Kev's Cush drive rubber mod using inner tubes. If there's a lot of play then it may be worth replacing them.
Other than that I don't know if Yamaha were as light handed with grease as they were on the Tenere's in the steering head bearings & swing arm.
Otherwise if it's only just been serviced & in good condition then just ride it & enjoy while you get a feel for it.