Grasshopper has problems to offset surface from Rhino

I notice that GH has always some problems with surface offset, it doesn’t seem to be able to follow the orginal surface’s normal direction. Is there any improvements in Rhino 6 about this issue or some way to solve this problem? (3.6 KB)
wrongOffsetSurface.3dm (109.6 KB)

Currently I’m still work on Rhino 5.