Odd Loft: Extends Beyond Frames

In the attached file I have a set of similar curves:

When I do LOFT on the curves I get this. I am curious what the loft is extended beyond the first frame.

Problem Loft.zip (23.0 KB)

Hm - I do not know why it does that, exactly but the last curve on the right is rational and the others are not.

Loft is happiest by far, with matching curves.