I have a question concerning the cooling system in my 2001 540i Sport 6spd. The car has 90k on it. About 1,300 miles ago I had the coolant flushed and new coolant added. The last few times I have driven the car, the CHECK COOLANT LEVEL warning indicator has popped up on the trip computer. I have checked the level and it appears to be fine. This morning, The thermostat in the car, which I was under the impression is utterly useless these days, actually moved up to the 3/4 position on two or three sperate occasions during my 45 minute drive. The needle did not stay at that level, and returned to the mid point. I was not driving the car under any "extreme conditions" as the BMW owners manual references may cause a change in engine temp. Any thoughts on what issues I should be looking for? The car is not driven daily, and can sit for a couple of weeks at a time. Hence, the coolant was changed in Oct. but the car has only been driving 1,300 miles since. Thank you in advance.