its a anti hijack system, many modern vehicles have this its to make sure all the doors are locked when you shut the drivers door or start the engine, its to stop someone climbing in the other side uninvited ...My Peugeot does it but only after its been driven for 1-2 minutes, most vehicles allow it to be deactivated in the vehicle settings.
I have seen this or similiar happen so many times whenever i leave an engine running (or work on a car) i always make sure the drivers window is open.



