Is this a bug in .iges file from MoI or not??

 From:  boatstalker
In need to convert my work created in MoI to .dxf 3D mesh

Using Prosurf for this purpose results in shapes originally trimmed or cut away in MoI to reenter the scene. Here is an example: Picture1 shows the funnel created in MoI and saved as .iges. Picture2 shows the .iges as it look when imported to Prosurf. Picture3 shows the funnel after it has been saved as .dxf 3d mesh in Prosurf and the resulting file opened up. The top of the original coneshape created in MoI and cut away has had an unwelcome comback. Is this a bug in MoI or in Prosurf? P.s. Attaced are the appropriate files resulting from the procedure described above.

Thanks in advance,