Catia ==> Abaqus, IGES import issue

I have an issue with opening IGES (from Catia) in Abaqus. I have uploaded a picture: figure 1 shows the imported geometry, segmented for the mesh. Figure 2 is the issue, additional edge segments are created on surface edge. When I apply mesh seed,1 per edge, on the model it creates additional nodes on the edges of my "wanabe elements". Note, no such nodes or segments are created when imported into Patran or Hypermesh. Figure 3 shows the effect of these nodes on resulting mesh, degeneration of otherwise fine quad elements.

I am not looking for manual solution of how to fix the mesh. I want to understand what causes the additional nodes to appear in the first place and what could potentially prevent their appearance. I would be grateful for any theories or suggestion on the matter.