It'll be fine then, and FWIW i suspect the 6V thing is just so it can be compared with other motors, at 6V. As we have a variety of batteries that can be connected up to the ESC/Motor, all of which give different voltages. And all of which are over 6V.
http://www.racing-cars.com/pp/Manufa...GM97284.5.html
Shows a more complete spec for a "similar" motor.