Noticed this the other night and not sure whether it's by design or luck.

 

In the S2, when my kids had the rear interior lights on at night I could see them in the rear view mirror and it was annoying as you can imagine.

 

However in the S3, the rear interior lights are slightly angled so I can't see them in the rear mirror. So much so that I didn't even know they had them on until I locked the car and noticed they didn't go off !

 

Simply clever?

 

 

Yes indeed. We found out in the same 'accidental' child-masterminded way that you did.