Digital BW, The Print

My R1800 uses the 3MK approach, ie Eboni ink in the two black and the
glop positions. The other five positions contain the clear MIS
cleaning fluid. When I run a nozzle check (which I do every few days
to keep the nozzles flowing) I get good results on the two black
positions and a nice checkerboard for the glop cart. Up till now, I
couldn't see whether or not the other positions check ok since the
fluid is clear. 

But lately I'm getting some faint lines in the red position. (This is
even after running the cleaning procedure.) Why would coloration show
up in this clear position? The red cart is the one right next to the
PK position... might there be some sort of bleedover? Anyone have any
comments on this? Thanks all!

My prints are fine, by the way... am using QTR to print .tiff files.