[Freesurfer] Irregularity in white matter vertex spacing (freesurfer 6.0)

We ran freesurfer 6.0 on some 0.8mm data and we are seeing patches of cortex with very sparse vertex coverage. I'm attaching an example (_fs60.png) showing a patch on the inferior bank of the calcarine sulcus. This particular issue doesn't seem to occur in freesurfer 5.3.0 (_fs530.png), which was run after downsampling anatomy to 1.0mm.

Is this a known issue with 6.0? Is there a straightforward way to fix it?

Similarly, in both versions we often see small "clumps" of really dense vertices (*_fs60_zoomed.png). Is there anything we can do to clean these up? For our application, we'd really like white-matter vertex spacing to be as "regular" as possible.

Thanks! -Keith