Anomaly in the blend surface command: bug?

In the Rhino 6 wip, i make a blend surface with built-in story history. Subsequently, by moving the surface (a) (it is noteworthy to rotate it, even a little), a strange artifact is highlighted at the seam point of the blend surface, such as a small crevice. Is this a bug?
Check it out, please.
anomaly blend surface.3dm (1.3 MB)

Hi Davide, I see that on your file but if I make my own blend it does not do this… still poking.

@davide76 It looks like it works better if you use the Natural setting when lining up the seam points. The edges start and end in about the right locations but the Automatic guesser on the seam point for BlendSrf chooses a different location for the larger edge. See what happens if you use the Natural option…


Have you tried to rotate the srf (a)? In the seam of the srf blend you create a strange fold, I do not know …