And finally (?)
Even if the linkages are all tight and stiff and not bendy at all, the surface can STILL flutter if it can be flexed away from the point of attachment of the horn (ie the surface itself is not stiff)
IMAC models sometimes use 3 servos per surface.
Ailerons with torque rods into the fulselage can twist considerably (and flutter).
The dead certain cure is not to fly so fast.