Digital BW, The Print

I just picked up a very fine microbanding, really a cordury, parallel 
to shorter edge, but only in shadow areas on Eclipse Satine 190 gm. 
I'm printing using Paul's curves for 2880 dpi. I've never seen this 
before. Only thing I can think of is k cart is a little low at 10% 
left (no CIS or CFS in yet).
Thoughts?
Jm H.