I have to say i get the same on mine. Its only ever happened twice, and both where when changing from 4th to 5th from the redline.
Because it's not happened since, I put it down to the fact that most of my miles were city miles, and that the permanent stop start may have glazed the facings a little (don't even know if this is possble?) - because after a good hard drive, it doesnt do it. If it was the clutch on the way out, i'd expect it to slip when launching from 3-4krpm drops, which it doesnt.