I just bought a used Bushnell Holosight (made by Eotech). The reticle is the ring plus dot. The dot is sharp, but the ring appears grainy, like it is made up of odd-shaped pixels. It looks this way at any illumination levels. Is this normal? or do I have a problem? Thanks for input.

It's perfectly normal. Once you begin using it, you won't even notice.

Focus on the target and not the reticle. Once you do this, the reticle will appear crisp and clear.
Hope this helps.

This "grainy" appearance is a phenomenon which comes from the Laserlight used to produce the reticle. Since it is uniform wavelength light, it "kills" itself in some incidences. Those are the tiny, black spots, called "speckles". Focusing on a distant target instead of the reticle itself, as already mentioned, helps to reduce this effect due to the reticle being out of focus of the eye then.