The rear wheel spinning while on a centre stand and in gear is normal, its called clutch drag and is not a good reason to start thinking you have a problem, check the oil first, if it is dirty change it. 25k miles is not really enough to wear out the clutch slip rings and friction plates unless riders have been slipping it alot or holding the clutch in for long periods of time. A better test is to sit on the bike, off the centre stand and drop it into gear with the engine running at idle, you should get a jolt when putting into gear but should not have to use the brakes to stop the bike moving forward, if you do then adjust the cable first.