Hi Jono,
All Beta gauges are notorious for odd and incorrect readings, although strangely,
they seem to continue functioning in some manner or other.
It may be worthwhile renewing the sender unit in the head, these can also give
erroneous outputs.
I've had this happen to me, when I was on the way down to France in the Spider. All of a sudden the temp gauge moved into the red and I quickly stopped. Did a full check and all temps were normal. Replaced the errant sender as soon as I could.