i have the same bike and also experienced this problem!
Its happened twice both times it was on the same long climb that has very steep at the finish, the revs were quite high as i rode over the top and as i apllied the clutch it just carried on, i shut off and apply the clutch again and its back.
i dont seem to notice any lightness on the clutch or any other problem for that matter!
a bit scary to say the least as there is a shear drop yon side of the climb ?
Im gonna take a look at the advise already given but just thought i would mention it
regards
den