Honestly, I'd say it's probably from the temp change recently. I have a few persnickety phal's that will get bud blast in the summer if we turn the AC on for even a few hours. It's always a bummer. Others don't seem to care. If there's one thing I've learned about orchids, is that they tend to do what they want to do, when they want to do it! They sound pretty healthy to me.