I've been noticing some dust on my rear wheel when I get in from a ride, so I check it and the wheel is hot to the touch, much hotter than the front. The brakes aren't dragging and there's no abnormal wear on the pads. This has been going on for some time. I just finished a much needed brake flush, hopeing that could be the problem. No such luck. I,m sure I,m not riding the brakes and I've put the bike on the center stand as soon as I get home and with the engine running, no brake drag. Is this normal? Any ideas?