That's good to know :)  I had the same problem the other day and couldn't figure out what the problem was. I wanted to get in there and clean off the camera lens,  LOL  That shadow min bias was probably the problem for me too because as soon as I changed light sets the black lines were gone.

I'll add this to my lighting bookmarks thread.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi