Your stick is spiking. Add damping to it in the in game interface.
I did damp both my X and Y axis and it seemed to settle the matter some. However some planes just seem to generate this message more than others for me. F4U4, Typhoon for example. I am wondering if my flying style in my more common rides(Spit 8, 9, 16 & Pony D) just do not translate as well for these planes.