Mysterious chunks being generated miles away from the edge of my map

Hi all,

I've got a fairly large map with ~111k chunks. A few days ago I noticed my cartography was failing. After looking into it, I realized that the images that were being created were 40,000 pixels wide!
Last night I went in and deleted all of the chunks outside a radius of 3,000 blocks from my spawn point.

However, today I've noticed that the majority of them are back! Some of these chunks are thousands of blocks away from the edge of my map!

Does anybody have any idea what could be causing this? The only plugin I'm using is the one I'm developing, and it doesn't do anything involving loading chunks or doing anything in remote locations, so I can't fathom any reason why chunks should be generated so far out.

Attached is a pigmap screenshot that shows just how far some of these chunks are. Some of them extend 3x as far as what is pictured here. They may be a little hard to see, sorry: http://i.imgur.com/SmI0P.png

 

Yeah, over the last few weeks I've had this problem too.
It's really annoying, makes generating a Cartograph image look terrible unless I edit it.. And it can't be good for hard drive space.

So far I've just been occasionally using a map editor, and deleting those chunks manually.. But I really hope this gets fixed soon.