Can someone explain what AA is doing with its auto pairing? Here is what I have observed:
1.) If the phone is already paired with the Pioneer, and currently connected, AA uses that pairing/connection if you then connect the phone to the USB port.
2.) If you shut the car off, leave the phone plugged in, on restarting the car you get another pairing created, and the one pairing you had before is gone.
3.) If Bluetooth is not on, plugging the phone into the USB port will turn on the phone's bluetooth, and connect to the Pioneer, usually with a new pairing.
While I guess this can be seen as a convenience to automatically turn on Bluetooth and re-pair your phone when you connect to the USB port, it pales in significance to the inconvenience associated with re-pairing my phone and resetting it up as a trusted device when I choose not to use Android Auto on a short trip. Plus you have to make sure your phone is unlocked before plugging it in anyway (or nothing happens), so it's simple to see if Bluetooth is on at that point.
And while this may be due to bugs in Lollipop 5.0, I know that if my phone is paired with the Pioneer, and I do not plug it into the USB port, that pairing auto-connects via Bluetooth as a trusted device every time.