This morning, I unplugged my car, closed the charge door securely. Got in the car and started it. I just had backed out of the driveway and setting up my waze directions, when I first heard the ding-ding-ding warning tone. When I checked my dashboard and the console display, there were no warnings I could see. I gave it to a fluke and kept driving. Got on the freeway, after driving about 12-13 miles, I heard the same warning tone with nothing to show for it on either displays. It is now bugging me what this could be. Any ideas ?