Absolutely untrue, in all respect to the tons of digital servos out. Digitals always make noise because they are constantly tracking their position. Standard servos correct around every 20ns i believe where digi is constant. My 1004SE Graphite can be a freaking chatter box at times, because every servo is digital.
A grinding noise on the other hand could be bad. like Hubber said, grind could equal partially stripped gear. Take it apart and look at your gears if it sounds like grinding or slipping and catching. Also always check to make sure your servo horns are tight. They will ocasionally work loose , especially plastic.