I agree with these guys. Check the front servo/band adjustment. When I set mine, I pull hard (by hand) on the lever and set it to 5/16" using an allen wrench as a feeler gauge. If it is over 3/8" it isn't right. Your symptons could be a servo seal too (or another seal).

I wouldn't get too excited over that small amount of debris. But check for steel vs non-magnetic stuff.