the stock bridgestone rear tire on the early 950s had a lifespan of about 8k miles. not sure which year Yamaha started putting Dunlops on them, and not sure of those lifespans, but i'm guessing it's pretty similar. how are you checking the tread? are you sure you're looking at the wear indicators correctly? how well are the tires gripping the road? any bald spots? do you see any cracking on either tire? how well is each holding air pressure? regardless of the mileage, they are now 3 years old and i'm guessing the rubber is significantly harder now than it used to be. motorcycle tires in general do not 'last' as long as car tires no matter how few miles you put on them.
my advice would be to have an expert, mechanic, or someone who's pretty familiar with bikes to have a look. you could take it to a dealership, but they're main focus is to make money.