Six years ago, I had this same issue, and it was resolved.
However, the gauge is acting goofy in the same manner now. Started on 8/22. This time, there is no loss of coolant, and the engine is running just fine.
While sitting in stopped traffic, the needle would jump up to hot, and the check gauge light would sometimes come on for a couple of seconds. The needle would then fall back to the mid-point. This would happen quite often.
When traffic would move, and I would start to accelerate, the needle would head back up, but not as far, and then settle down again.
On the freeway, everything was hunky-dory. The needle would stay where it is supposed to be.
This hasn’t happened when driving around town. Just after many highway miles.
We got home yesterday just fine.
I checked fluid levels today, started the truck, and watched for any sign of leaks, and saw none.
I did notice that the temp gauge was sitting very far below the cold level.