Thank you for your replies.
Yeah, I am in voxel mode. The problem is, I had the model at this detail and it worked just fine, in spite of voxel mode, as I had quite a bit of detail on it. I *think* the problem occurred when I merged with another layer (I merged that layer into the main model, which has a rather high resolution), but I am not sure when exactly it happened.
I tried upping the resolution, Smooth All, converting back to surface mode, and a few other things, but it doesn't seem like the model can be salvaged Regardless of what I do, the banding stays, even if I smooth it over with the smooth brush itself. Looks like I need to start from scratch.