When testing indoors with the TX antenna collapsed, its possible for signal reflection to make the servos jump around a bit. Sometimes this is large, fast movements... sometimes its just a little bit of a buzzing noize form one or two servos. So retest outdoors with the tX appx 6 to 10 ft from the airplane.

A servo that is bound... (prevented from hitting the position the tX is telling it to) may make noize, and may grind its gears apart. (very bad) Set the throttle stick to center and if the noize goes away, you probably need to adjust the throttle linkage. Also if it goes away when you bump a stick and then let it recenter... there's probably some binding in a pushrod path, or a hinge out of alignment.

There are so many other possible causes... it would be really helpful in finding the noize source for you to take the plane to a hobby shop or get an experienced modeler to look at it. You do want to cure the noize if possible. Any time a servo is making noize.. its drawing more than idle current... that means shorter flight durration before the batteries are DEAD.