QTR-Quadtone RIP

I've been attempting to do some 7 x 5 BW note cards with the
Epson 1400/Piezography inkset and QTR (OS X Tiger - latest QTR).

I was testing with some sample RR 230gsm GC Matt, and one of the test
images had a bottom (as printed) margin of 1/8 inch. At the very
leading edge of the paper there is a band of black streaks - like the
head was dragging or scuffing - almost looks a line of shadow/dirty. I
can't see any burr on the paper with a glass. Another card test with a
3/4" margin (same paper) printed cleanly.

Am I running the margin to tight? Or could this just be a rough edge
on the paper? For 3800, there is a setting for paper thickness - the
1400/QTR seems to have no such adjustment. Or did I miss it?

=Alan R.