ExplodePolySurface Error

Hi everyone,

I am attempting to explode poly-surface in grasshopper python.  I have written the the following script to change the x/y dimensions of a profile then extrude the profile into a solid block.  For the next step of my script I need to select the back surface.  However when I do: rs.ExplodePolySurfaces() I am getting back only 3 surfaces the two edge profiles then a joined trimmed surface for the extrusion in between.  When I run this code using the Rhino Python Editor it properly explodes the polysurface, but the same action does not occur when I am using grasshopper-python.  

Any assistance would be greatly appreciated,

Thanks,

Peter Schmidt