Digital BW, The Print

I just started working on some profiles for the new Moab Entrada 
(white) paper using QTR and the Epson 2200 loaded with the UT inkset.  
The first calibration print consists of single channel ink prints of a 
21 step gray wedge to establish ink limits.  On this print I noticed 
severe mottling in the dark gray (C position) and medium gray (LC 
position) wedges (from the midtones up to 100%).  All of the other ink 
position wedges looked fine with no visible mottling.  I didn't see 
this phenomenon on EEM, so I assume it is a specific paper/inks 
interaction.  The composite wedges look OK, so this may not be a major 
problem.  Has anyone else used the UT inks on this paper and noticed 
this effect?

Carl