Spheres Jittering on 3D Surface on play (Non Moving Spheres)

I am having an issue which shows itself throughout game play, in which i have spheres on a Cubic Surface.

On start the spheres start to jitter, as in the Y Coordinates change very slightly going up and back down.
The Spheres are not moving, only jittering. also when i turn the Physics auto simulation off this stops happening.. when turned on this anomaly occurs and i would prefer it to be on..

Here is a Video Showing the anomaly.