OK, so, can anyone explain to me the effect I'm seeing and how to deal with it?

I've printed a bunch this way, and thought that maybe that was just life, but looking at prints from other people, it doesn't seem to be the case.

Specifically, what I'm referring to is the...ridges(?) I see in the preview that I don't see in the actual file. I'm guessing there's an S3D setting that can help with this, but I don't know what that is.

cap1.JPGcap2.JPG