Digital BW, The Print

I've been printing b&w with the epson 1280, NMC CIS and MIS dye 
inks.  The neutralality has been looking fantastic on LPM without 
special profiles.  What I'm seeing, however, is slight magenta 
overspray on one side of the print, perpendicular to the head 
movement.  Head cleaning doesn't seem to help, nozzle checks look 
fine, but when I make a print, a slight line of magenta is visible on 
one edge of the print, the other 3 edges are clean and neat.
I called epson about it, and they are sending out another 1280, somI 
will replace the cart holders and transfer the CIS.
My question is have others had a problem with overspray on the 1280.
The prints themselves look great, nothing is out of register or 
allignment.
Last night I put some windex on the parking pad sponges and let it 
sit overnight hoping that might solve the problem, but no such luck.
I don't recall seeing this problem when using oem carts.
Could the CIS be causing this to happen, I hope not because I love 
the MIS Dyes and the CIS works beautifully.
I seem to recall someone saying that the 1280's often "oversprayed"
Is this true or am I imagining it.
Any info would be greatly appreciated.
TIA.
David