I think you'll be fine. The over voltage just gets dumped to ground. Your battery is not getting cooked.
In this case anything over 14 volts means the battery is getting charged and not being used to run the car electronics in a long, slow drain. Voltmeters on cars are fairly sloppy. They have to be since the charging rate changes so much due to engine speed. They're charging or not. When you see the meter take a dive or reading low then you know there is a problem.
