Yellowing leaves on Masdevallia

My Masdevallia sanctae-inesae that I bought in May from Ecuagenera has seemingly been healthy; it's been putting out plenty of new leaves and roots and has successfully bloomed. Until recently, there's been the occasional leaf that will become yellow and drop. But now, it appears as if most of the leaves are beginning to yellow.

Conditions are as follows:
- 69°F max daytime, 52°F nighttime (just yesterday changed to 71°F day and 55°F night)
- misting twice daily
- computer fan running for ~12 hours in intermittent intervals
- potted in sphagnum moss

About a couple of months ago, I reduced the amount of time the fan runs. Would anyone like to confirm or refute my hunch that this is an air movement problem? As well, what measures can I take to minimize the damage to my plant?

 

I using a wine chiller as a terrarium. I'll adjust both the fan and the watering and see how it goes.

 

Watering is done via a misting system that uses deionized water. It's in a terra cotta pot with sphagnum moss, which is probably retaining too much water. It likely didn't completely dry off before the nighttime drop. I cut down on the amount of time the mister runs each day and changed the timer on the fan so that it's running all day, except for brief periods after misting. I certainly hope all of this helps, since this is one of my favorites. Also, after the bloom finishes, I'll be putting it on a cork mount.