Like Roham said...... sounds like you have too much humidity. It also sounds like you have a really tight sealing humidor. First you need to SALT TEST your hygrometer, your hygrometer could be off so you are not getting a correct reading. CLICK HERE

I believe you may have ruined the Credo with mold the first time, that's why he mold came back. It was probably still on the Credo. You might need to either open it up and clean it well or throw it away and by something else. I would not recommend the Crystals but BEADS work really well and alot of people use them. You can get them here..... CLICK HERE.

After you have Salt Tested the Hygrometer, put it in your humidor with nothing else, the wood might be saturated and unable to absorb anymore water. The way I stay away from mold growth is by using 65% Beads and keeping my humidor at 63% - 65%.... Stick smoke really well at that RH..... If you find you need to bring the RH up, cut a small sponge (anti-bacterial, if you can). Cut it into about a one-inch sqaure and use distilled water. That's what I use when I need to bring th RH up in my 54 Qt cooler.

PS..... Congrats on th Wedding