I seem to have hit a bug in the Prius firmware. I had a passenger in the back seat. She got out and closed the door. I think she closed it as I was already driving off. The yellow triangle with the ! in it turned on and a loud beep started, but there was no indication that the door was not closed properly, which was my first thought. Nothing I tried got rid of the warnings, until I stopped the car and power cycled it. Rebooting cleared the problem. Has anyone else run into something like this? Oh, and how do we get firmware updates?
I would have to believe since I tried this with my car as well, while your car in in "D" just stop the car and open the Drivers Door. You will see the Yellow Triangle and ! point lighted. I would tend to believe that the person opened the door with the car still in "GEAR" thus the warning. In most cases you should hit park...it's just a second more to do that. So does it need a Firmware update?? I think it's just way it was designed. If the Triangle didn't clear something tells me the door was never relatched correctly. As once I closed my drivers door on my test the Triangle went away but NOT until it was latched correctly.
When the triangle appears I believe there will also be a description of the issue in the Multi-Information Display. Do you recall?
When I have the driver's door open while in [D] I get a message that the battery can not recharge while in [N] or some other such silliness. I took a picture and it's floating around here somewhere.