That is a very large servo. My tests with a smaller one showed the 5V supply going up to 8V at the end of servo movement. With your large servo it will be much worse. I suggest you use a separate 5V supply for the servo, or else connect a 6V power Zener diode in parallel with it to to clamp the voltage.

Edit: also, the motor current drawn by that servo may exceed the rated current of the regulator. In theory it's short circuit protected, but its best not to rely on that.