Parmetis and graph nodes connected to themselves

I have spent the last day chasing down an "assertion failed" in parmetis that apparently occurred because every node in my graph was connected to itself.
I don't know if you call this a circular edge, or a 1-node edge, or what. Removing these edges from my adjacency vector caused the program to run correctly.

The assertion failed in Match_Global and appeared that certain ranks were asked for information about nodes that they did not own -- I can send on more information if this is helpful.

My real question is this: is it surprising that this kind of graph would cause ParMETIS to fail? It partitioned fine when run in serial.

thanks,
Craig Tanis