Go have your timing belt changed as the manual calls for it at 105000. I wouldn't try to squeeze the other 5000 although it is probably a somewhat conservative number that Nissan has set. Its always cheaper to replace a timing belt before it breaks. I'm not sure if the VG33 engine is a valve bender but I wouldn't want to find out by personal experience. If other damage does not occur when the belt snaps you still at very least save yourself a tow bill. Also as Guido said may as well change the water pump as well because they will have it off anyway and it will save you some labor charges down the road. Congrats on you 100K. My 03 just rolled to 10K