Other things to take into account:
1. Have you added a significant number of cigars lately? OR even a couple of Boxes? You can get cigars that are VERY dry and they can inhale humidity. For the boxes same thing. You get a box that is dry your humi is having to pour it out not only to the 25 cigars in the box but the box itself as well!
2. Have you checked the door of the tower itself? Sounds stupid but with my tower awhile after I first got it I noticed the top was always 4-5% lower? By accident really I was pressing on the door and noticed that the top had some give to it. So, I went to Ace Hardware and bought the good old brass flip latches and put one on the top and bottom of the door and walah problem solved there. Since that little fix not only did the top even out IT also added over a full weeks time to when I had to refill my Humidifier. A little give in that door can make a HUGE difference. When you think about it Wood+Humidity+Temperature classic formula for warping even the slightest amount. Your tower isn't SOLID Spanish Cedar just lined with it.
3. How good is the ventilation to your drawers? Once again mine all of the ventilation originally came from a 1 1/2" gap between the back of the drawer and the end of the drawer itself. There is about a 1/4" gap loose on the tops of the drawers themselves. Didn't like it so I drilled 1/4" holes in the Top and Bottom shelves that separate the drawer section. Once again better results.
4. Has your weather changed lately in any drastic ways? I live in Colorado!! About a 8-9 days ago it snowed about 90% humidity! Today it was 83 with 16% humidity. I know you think OK no biggie that OUTSIDE not inside. True but people love to open up all the windows in the house and air it out when the weather gets nice :) Had the opposite issue when I lived in Shreveport LA! There I actually had to put cups of the crystal kitty litter in my humi's to LOWER the humidity!
I know that's a ton of crap but sometimes it really is the simplest little things. Your dealing with Temp, Humidity, Humidor, Humidifier and of course the cigars! One, all or any combination of them can easily cause a 5% change. I do agree with Watchman give em a call! Hell worst case they call it a bad batch and send you some freebies