Last year we noticed that the trunk light in our '11 335is turned itself after some undetermined period of time.
My wife came home from work one day, opened the trunk to unload it, and then saw the next door neighbor out in front, so she went over to chat. I went out some time later because I heard that she was home but hadn't come into the house yet. When we walked back to the garage, the trunk light was off. Just to make sure that the trunk light hadn't burned out, I closed the trunk and when I opened it again it came on. I didn't know that it did this. We've since confirmed this on at least a couple other occasions. I definitely didn't know it was known as "workshop mode".
(Did you spill something in your trunk?)