Gempak error [GEMPLT 1] NCTRLP - Broke out of contour loop.

In working with scripting Gempak 5.7.1 my scripts occasionally die with the 
following Gempak error:

[GEMPLT 1] NCTRLP - Broke out of contour loop.

When I view the graphic output it seems to be mostly drawn except for a small 
piece of contour line. This error persists when run in 5.9.2. I have searched 
the archives and Google and the only instance of this error I find is in the 
Gempak source.

Can anyone provide me with more information about this error? It shows up on 
random occasion whenever contours are requested.

All of these scripts run gdplot2 to generate giffiles from gridfiles of 
forecast runs.

Edgar Bering