Bongo Fury

I've recently fitted a Mason alarm, I've calibrated it to about the 4.5 region and tested it on a run up to Carlisle with no problems at all. But today I took the Bongo out for a run to charge the battery up.
It was up to normal temperature at 1 o'clock position before I pulled into the petrol station, filled it up and when I started it up again the alarm went off straight away and the needle was nearer to 2 o'clock, I pulled off nervously and prepared for the worst (I can roll all the way home from the petrol station if required) within 100yrds the alarm had gone and the needle was reading normally, should I be concerned?

Mark

Check your water level.
Its a start.

When you stop your engine, the temp of it can rise by as much as 10 degrees due to the lack of airflow. This is normal.
Now you have the Mason fitted the gauge is more sensitive and shows this rise. Before it didn't.