That happened to my bike before, except it is when I started to brake ie. lightly tap the front brake. I honestly did not know whether it was the bearing or the pads though.
Few thousands km later I replaced the brake pads and it disappeared apparently race pads were fitted.
andi - Red GPZ900R, GPZ750R1, KLR650 Tengai, KLR250 "my dad's motorbike is cool it is all ways clean.oheter pepole' s motorbikes are't like my dad's one it's because their is one not always clean." -ariel circa 2007 http://GPZninja.blogspot.com/