Correct me if I'm wrong (my wife does this frequently!), but I always thought that when you pulled the clutch lever in, your bike was essentially in neutral and the rear wheel should spin freely, not powered by the engine. This I thought meant the clutch was DISENGAGED....
Am I wrong? My wife would be overjoyed once again!!
No you are not wrong...but this has nothing to do with the wheel spinning when it is off the ground and the bike is in gear...AND the clutch is "disengaged".
Kind of hard to give you a good example of what is happening, but think of two pulleys connected with a belt. You turn one pulley and it turns the other..which lets say turns a huge metal fan. Now, if you loosen the belt slowly by pushing the pulleys together, at some point it will not be able to turn the big fan but will slip on the pulley it is connected to. The weight of the fan (it's mass) has overcome the friction and until you tighten the belt up a bit, the fan will not spin..BUT if you were to somehow disconnect the big fan from its pulley. you would greatly reduce the mass ...and even though the belt is still slipping some, it would start to turn that pulley..because the mass is no longer working against the friction. You could take your hand and stop the pulley with very little force, causing the belt to slip again.
Same thing is going on with your clutch..the plates are still making very light contact even when the clutch lever is pulled in. But instead of just mass like the fan, it is the counter amount of friction of the wheel touching the ground. Put the wheel in the air, you lose that bit of "holding power" and the wheel will begin to turn slowly...opening the throttle most likely will not make the speed of that wheel increase by the way...because raising the inertia of the "drive" clutch plates might actualy make them slip more when set against the "driven" plates..whose inertia is the same.
Oil does factor in this as the oil between the plates is causing the actual contact. Not really sure if how much oil tempature factors in here, but it is the "Stiction" of the two oiled plates that causes this whole thing to occour. (Take a small thin flat sheet of of metal and coat it with oil, slap it against a smooth wall and let go..it will slide down the wall...but ..it is sticking to the wall...)
When you are sitting on the bike and the wheel is on the ground, your weight, the weight of the bike and the contact of the tire on the road all increase the static friction of the wheel so much that it overcomes the light input to turn, and thus you would never notice it. Raise the bike off the ground and you remove all that.
So..as I said, normal , do not worry about it.