Yes, my beads that are exposed have discolored a bit, beads in pucks/tubes haven't done it as much. I imagine it is due to the two way nature and absorbing something from the wood/cigars that causes this, but that is just a guess.
FYI, It's actually hydrocarbons and other dust particles from the cigars and wood that cause the beads to discolor, not ammonia. Using tap water instead of distlled water also causes discoloration.