Digital BW, The Print

Hi,

I say this is off-topic because my question/issue has to do with some  
color printing that I've recently done rather than B&W (which I  
normally do).  I recently converted to MIS K4 refillable carts in my  
Epson 2400 printer.

I occasionally print color and yesterday was printing some smallish  
4" x 4" color prints on Epson's Enhanced matte paper.  I'm noticing  
that the certain areas of highlights or where there are subtle  
variations of a color (especially skin tones) that rather than have  
smooth transitions between tones there are "clumpier" areas of color  
or "splotchiness".  Hard to explain but it bears no resemblance to  
the image on screen (digital source).   My question(s):  has anyone  
else noticed this?  Is it a MIS ink problem?  an EEM problem?   
combination?

any insights or thoughts on this would be very much appreciated.

Jerry