So your talking about 46-79˚F , and I am guessing there is lots of moisture in the air along with rapid temperature changes. ? that would cause moisture to dissolve sugar on the surface of the chocolate making whats called a "sugar bloom" (it is not a mold). just sugar crystals running amuck. Most chocolates have enough sugar in them to be some what mold resistant, at least for more than 3 or 4 days. Good news is the chocolate is still good and you can remelt it , bad news is you have to remold it. Low humidity would certainly help.
Chocolate should be stored between 61 and 64 degrees F (16-18 degrees C), with very little humidity as possible.
There is also whats called "Fat bloom" that is caused by the crystalline structure of the cocoa butter breaking down and some of the cocoa butter migrating to the surface of the chocolate. (It looks kind of grayish). But that's caused from the chocolate being kept to warm, but that doesn't sound like what your experiencing.
You can try puting them into a tuperware like container, the newer ones have a air lock thing. That might help some.