Experienced a very strange noise today having just travelled a mile or so. Pull up at junction and my FL2 made a noise that mimicked a wedding car with tin cans attached. Travelled a further short distance to clear junction and noise evident on slowing down. Returned home and made inspection - found small granite stone from my driveway caught between offside front disk and steel back plate/ splash protector.
So if you experience similar - suggest start by checking around the disks area.