I realise I'm replying to an old thread by I've occasionally had this (randomly found the gearbox is in sport mode when I didn't select it). I've come to the conclusion that it happens by accident when putting the car in and out of drive/reverse while manouvering. Having said that, I could have sworn it's done it on its own once or twice. I've never seen it change in front of my eyes though (only noticed it later on) and it only happens very occasionally.