Sounds like I have nothing to worry about.
The light came on in identical circumstances, once on the way to Devon and once on the way back, when I was in heavy slow moving traffic for what seemed like an eternity and then flat out acceleration on short uphill stretches of dual carriageway trying to get past as many lorries as possible before the single lane road started again, wife only swore at me once so she was probably asleep the first time.
Thank you for your replies.
