I have a couple servos that are buzzing on my raptor .50. Is this a normal thing to hear? Not all of them are doing this, just a couple that I noticed. The servos are S3152 and the tail servo is a<span style="font-weight: bold;"> S9254</span>

What would be causing this, or is this just normal operation? There is no clicking, and the servos are getting there full range of motion with no binding or hesitation. Also they only buzz when you are moving them via the receiver, after a few seconds when you stop mving them the buzz goes away.

Any ideas or suggestions, I would be happy to hear them. Keep in mind that I am a beginer and this being my first build.