Rick, many varients could be the problem..
how big a humi? any recent adds?? (new cigar shipments)
location of humi/AC turned on in house because of summer heat? AC or Furnace will suck the humidity dry in no time...
sounds like possibly the last question may be the case??
with adding more cigars, newer to the stock.. it's good to toss in a humi stick to help stablize the humidor' 50/50 solution always works better also.. don't ask me why?? I just went from early american to now Climax beads myself.. their enroute.. I've read so many good things about them.. I had to twist my arm off and get some... but adding more cigars without adding additional Help IE: humi sticks in the mix will cost you a bit of RH until everything gets back to stable...
just my .02 cents
Good Luck
Hog