Out for a ride with @cruiser and @greminn on Saturday and about 2 hours in I noticed that my rev counter was reading about 3000 rpm too high (7000 rpm showing in 6th gear at 100 kph/62 mph) when normally it reads about 4200 rpm. As I increased speed the revs increased proportionally. No other signs of weirdness apparent.

At the next stop I switched off and the rev counter needle stayed at 7000 rpm with the ignition off. When I switched on, it did its start-up sweep from 7000 right around the dial to about 6 o'clock on the dial (i.e. pointed straight down) and returned to 7000 rpm. It was almost like it had had its 'zero' position reset.

I switched off and back on and noticed the needle dropped to about 5000 rpm (then did its sweep), then repeating ignition off and on several times it progressively dropped each time until after about 4 or 5 goes, it reset itself back to normal, resting at 0 rpm, and then doing the sweep around to 15,000 rpm and returning to 0 rpm.

I haven't ridden it again yet, and will report on any whether this happens again. I searched the forum and found one other thread reporting similar (but not identical) behaviour, with no apparent solution or cause identified.

Anyone seen this before??

Yes, it's been seen before...particularly on the 1090RR series.

There has been success in resolving this by cleaning the multi-pin connector at the back of the display.
Use a good contact cleaner and then a preservative.

Was thinking it might be something like that