Parked rhe car last night. This morning all 4 windows were half opened (all at the same height) and the sund roof was opened about an inch???

It's cold here, so 100% sure they weren't left open.

Any ideas on what might have caused this ?

 

The window down and sunroof open is a function of the remote. If the unlock button was inadvertently pressed the auto open will activate.

The easiest way to avoid a repeat performance is to keep your remote(s) in a faraday bag. Find them on Amazon

 

Don’t you have to hold the unlock button a couple seconds for that to occur?

 

Actually you must press the button 2x within 10 seconds and then hold it on the second press. The fact that the OPs windows were not completely open indicates that the second press was not long enough to fully open the windows/roof.