Speedometer acting odd

[Zonder]

I have noticed twice on a long drive that my speedometer dropped a few miles per hour then back up again very quickly. Also I got high revs at one point think it was 5,000ish @ 80mph which normally was 3000 (I think defiantly not 5000 though!) I had cruise control on at the time which I switched off but it didn't get normal till I stopped at a service station.

Also the car was running normal temp and had plenty of fuel prob half a tank. I would have travelled over 100miles when I noticed.

I haven't had chance to check for fault codes (laptop broken) but should I be concerned?

 

[Zonder]

Managed to check the ecu and no faults have been logged.

I haven't seen this happen again but as I have been watching the speedo more I have noticed the power is going off on the lcd display (only happened twice) so maybe i just have a short somewhere. Not sure that explains the revs though.