I read this thread a couple of days ago and thought smugly "Nope, that's one problem I haven't got". And then today, for the first time in 5 months of ownership, it happened. It's just on the big touchscreen, there's nothing untoward on the circular multi-functional display (which usually shows parking sensor warnings as well). Nor do I remember getting the audible warnings that normally go with the parking sensors.
Now, my car suffers from the "Process system not responding" error and normally I cancel that notification; however today I couldn't be bothered and for the first time I just left it on the screen ... and suddenly for the first time I got the "Warning approaching object" error. I wonder if these are connected, ie the spurious "Approaching object" error is another symptom of an underlying android fault ?