Avoiding creation of unaligned intersected curve

I have a form which I created using sweep. I am extracting curves along its length by adding perpendicular frames. Unfortunately, I get one extra unaligned curve which is coming as a result of perp. frame intersection.

How do I stop this unaligned curve from getting created? Of course I can find it from the data tree and remove it. But if I figure out why it is being created and stop it in the first place will be more efficient.