My previous m135i used to auto dip the passenger wing mirror when reversing and put it back to normal once back in a forward gear.
It looks my S3 does this if the mirror select dial is set to the passenger mirror but it never goes back to normal position after dipping unless I move the mirror...
I've had this when I used to keep my phone in my shorts leg pocket. Going round corners it used to press against the volume control button in the centre console causing the radio to skip frequencies.
Took me a while to figure it out lol