My suggestion would be to start by recalibrating your hygrometers. As long as nothing else has changed that would be the most likely issue (just getting a bad reading)
One other question for you. Did you recently buy some new cigars that you put in there? I have found I the past that when I get a box or even a couple of fivers from a retailer that keeps them too humid it will affect the readings on my hygrometers by a point or two for a few weeks because it is introducing extra humidity (through the new cigars) into my system. After a few weeks they will acclimate however and everything will be back to 65. I. Also use kitty litter and have been VERY happy with how it keeps thing regulated for me. I travel quite a bit for work and never have to worry about my coolers, even when I am gone for extended periods of time.