Brep.Trim(plane, tolerance) produces invalid breps?

Hi!

Occasionally the Brep.Trim function produces "broken" Breps if I use it like described below:

I have a polyline "pl" (simple and convex) and a brep "FoamBlock" and I want to cut away parts of the brep that lie outside of the polyline.

How can I avoid uncapable breps that have very small naked edges?

List<Point3d> pl; // Path along which I want to cut away parts of the brep 

List<Vector3d> norm; // Cutting plane normals

for (int i = 0; i < norm.Count; i++)
{

Plane pCut = new Plane(pl[i], norm[i]);

Brep[] cut1 = FoamBlock.Trim(pCut, 0.0001);

}