Angraecum alabaster leaf drop - I think something is wrong

[PlumCrazy]

Hello! I understand that leaf drop is normal, but my plant dropped three leaves today, and something doesn't seem right. The leaves didn't yellow first. Conditions:

- mounted, in a terrarium
- 2 small fans on all day
- humidity was at 70% before watering time then went to 85%
- misted daily with distilled water

It's been in there a few months and seemed fine. I have increased humidity a lot the past week because I'm trying to establish some new moss I bought, so I've been spraying the moss 3x a day (but not the orchids, although obviously some gets on them) and it's probably a few degrees cooler (68 or so).

Should I be worried and if so what steps should I take? Thanks!