Removing power from a servo will remove all torque force from the servo and only leave gear friction to resist any load changes. Also removing power with a servo output signal still active will cause 'phantom' current to flow via the output pin if the arduino is still powered up. So detach servo command and a digitalWrite low should be performed. In all likelyhood when re-powering up the servo and re-attaching the servo library will mostly like cause a jitter or worst.