Ken,
On the negatives with this line, is the line where the film had stuck up out of the hole?
I had this problem with my first attempts at using pyro developers. I didn't realize it until I noticed that my 8x20 negatives had the marking of the inside of the tank, then I looked closer at the 8x10 negatives and found they did too.
I will say that I have not had this experience with Pyrocat-HD, only with ABC and PMK which as I found out, were not designed for continuous agitation.
Since trying Pyrocat-HD, I've had negatives that move inside the tubes of the tank and never had a development mark.