Digital BW, The Print

I'm not sure what kind of banding this is but it is very subtle and consists of 
graduated large bands 1-2 inches apart across the printed page.  I only noticed 
it after awhile under bright light and then only on this one 13" print with a lot 
of plain area like sky and sand.. I use Claytons BO setup on the Epson 2200 and 
have made a dozen or so prints with no apparent banding. I'm normally very 
pleased with the process.  Any ideas?
Art Schaefer