Curve from two surface intersection

 From:  Sharif (SR13765)
6698.4 In reply to 6698.3 
Hi Michael;

The orange surface created by sweep a straight line along a curve. I noticed that when I set the sweep option twist to flat I get the bump/wave at top and bottom of the surface. If the sweep option set to freeform the resulting surface is perfectly smooth. Is there any solution to this?

Thanks
-sjharif