Extra perimeters (or something)

[jwellman]

I'm attempting to print a vase using 2 perimeters and 0 infill. Around the interior sides of the vase I keep getting these weird areas. I'm not really sure how to describe them. They're not full perimeters and they're not infill.

Any idea how to get rid of this? I currently have infill set at 0, 2 perimeters, 0 top, 5 bottom.

Interestingly at 3 perimeters this seems to go away. At 1 perimeter it's even more apparent. It's like the walls of the model have a thickness. This is the model:
http://www.thingiverse.com/thing:85218

Thanks,
Jared