Oddball, no audible effect Lexicon MX200 glitch has me head scratchin...

Have a pair of MX200s on Profire 2626 DSP stereo monitor sends, coming back in on a total of 4 standard inputs, for sweetening the cans mix.
 
DSP level meters on the 2626 software show matched left and right levels for stereo inputs, or single levels for mono ins, panned dead center.
 
Most of the time the matched left and right levels continue all thru the chain, but once in a while, the MX200 meters show a significant mismatch, a couple three LEDs worth, to one side or the other, which in turn shows mismatch in the DSP return channels, and on the master fader meters,  hile the original input shows them matched perfectly.
 
A/Bing the left and right speaker I find identical SPLs at all gain ranges for the returning signals, everything sounds fine, but it just plain bugs me cuz I can't figure it out.
 
I know...it ain't broke, leave it be, but it bugs me.
 
Any ideas?