Hi Jason, you've got me puzzled now as my nearside mirror automatically dips when reverse is selected and I have the folding mirrors.
I've had a look in the manual and the way it reads by implication, is you push the mirror switch on the door panel to the position of the drivers side mirror, engage reverse and the passenger side mirror should dip. However, there is that pesky little '*' after the pre-amble which means 'depending on country etc.'. This doesn't explain why yours did dip then has stopped though. I'm pretty certain the folding mirrors have this facility 'built in' but there is no function within any of the i drive to cancel/activate the dipping.
I'm a bit confused TBH now. May be worth playing with your switch though.