Hi all, first post here so be gentle!
I'm having the exact same problem as OP. It all started couple a months ago, once the temperature here started to drop.
Bought my car last year in April and never had this happen before.
To my ears, it sounds like a vacuum whining of some sort, if that makes sense...I believe it's coming from the driver's side engine area (LHD car).
In my case, the sound doesn't go away if cruising around 50-60 kph, in normal traffic. Only after the car warms up AND I shut off the engine and start it again this weird noise disappears.
I already booked my car in for next week, will see what the dealer has to say about this.
I'll keep you guys posted!