When my dealer was helping me diagnose what I believed to be a cold weather performance issue the mechanic noticed that the water pump was cutting in frequently. He said there is a service notice about this (though they hadn't seen fit to notify me about it). When I listened carefully I could also hear the pump starting and stopping every few seconds though if I'd not been told what to listen for I doubt if I'd have noticed it.
Anyway, they had the car in and its fixed.
Peter T