I have it as well as did my K75S and R1100RS. The old cure was to drill a ventilation hole in the back of the instrument panel but I haven't looked at the GS set up to see how easy/safe this is. So I'm not recommending it.
hi mike
i've cured problem , i think ! i was a bit eager with the hose when washing her now i just use a light sprinkle over the clocks now,
all clear since.