"Gordysvette".....How cold was it when you started the coach? If it was pretty cold, your fuel rail heaters are activated and draw a lot of power, often causing the opposite situation, low voltage. You may have been pulling a lot of power for the fuel heaters and when they stopped, the coach glitched and was still trying to keep up. I would wait to see if it happens again. Just about everything has a computer attach and can do stupid things.
You can go into the codes on your dash by togging through your display window to diagnostics and see if it threw a code. Then call Freightliner with the code and see what they say. They're very good on the phone.
