. **The effect you see is sometimes called banding,** I dont think it's a problem with the display. I think it's the interaction between the layers. When I make a gradient in PS I tend to put "Dither" on. it  scatters the colours a little more.. the example shows a red-green dither. the effect is almost impossible to detect when the colours are so similar, having a dither in your gradient would minimise banding.

I would also try to avoid having exactly the same (duplicate/clone) gradient effecting another try shifing the effect a pixel or two across, this might reduce funky colour intereaction.

See if you can add little noise to the gradient, or have a look also in the render options in the  3D program, a bit of difusion in the sky could work wonders.