Hi Joe,
I'm assuming you only have the satnav displayed when you get in the car and turn on the engine.
If you use the selection buttons underneath the display buttons, to "list" your iPod content, you shouldn't be prompted by the warning screen.
If you press any of the buttons, ie settings etc, you then get the warning again.
When I switch my car on, I have the radio/ USB list displayed with no warnings.
Hope the above makes sense.