OK, remember how I told you that the plane was shaking as the engine ran, while the plane was on the ground (tied down)? It sounded as if the whole plane was vibrating, and you could see the horizontal stab shaking pretty good.
Maybe the vibration wasn't from the engine, but from flutter.

Can you see flutter when a plane is tied down to the ground?

Remember, pretty much the whole plane shakes. There is really no play in the control surfaces, except maybe some in the ailerons, but I'm not sure if this is a normal amount. If you take an aileron in your hand, and move it up or down, my servo arm turns immediately . But if I wiggle the aileron up and down gently, there is some play.

ps the plane could be heard to be making the same sounds up in the air today.

pps--Flight #4 today--good landing, no prop srikes! :-)