My D300 with a little over 8000 shots suddenly started acting weird today. I was out shooting dragonflies and had taken 10-20 shots with no problems. I decided to put on a Kenko tube when I discovered that all my shots were way too dark, at least 3 stops. I took of the tube with the same result and shot a few shots with +3 EV. Suddenly it was back to normal for the rest of the day although some shots were overexposed and some were underexposed. Has anybody experienced the same? Would cleaning the contact help or should I send it to Nikon for service? Bought in January 2008 and I'd rather not be without a camera in the dragonfly season.