TD5 Temprature dropped

Hi all had a good few months problem free not sure if i have a problem or not driving home last night about 17miles near to home temperature gauge dropped then went back to normal search online but most peoples temp goes up any ideas what could be causing this maybe a sensor any help would be great Thanks

could be a ****ty connection on temp switch or could be an air lock in the cooling system.first clean up the connection to see if it is cured and if not try bleeding the system.

Dont think id worry bout it unless its the other way round, never heard of an airlock that decreases the temp but you never know

Thanks for replies checked water today everything fine there will clean connections and wait and see what happens