Seasonal Changes or something to worry about with my Phals?

[akhenenra]

Hoping someone can tell me if this is something I need to worry about. I've had most of my Phalaenopsis orchids for around a year. They have all seemed very healthy in the time I've had them. In the last week or two though I have noticed quite a few of them have started getting kinda wrinkly leaves. I haven't done anything different in terms of the temp in my grow tent, watering schedule, etc. I water them around twice a week- they are in coarse bark and that seems to be good for them. The pots are clear so I can see that they have healthy roots. But the wrinkly leaves are worrying me. It doesn't seem like it's simply old leaves getting ready to be shed because they are not always on the bottom. Could this be a seasonal thing? I've never had this collection over an entire year consistently so I am not sure how they will respond to "winter" coming (I say "winter" because they are in a grow tent- I'm not sure they will even know it's winter right?). Any thoughts appreciated. Thank you.

PS- I have also noticed that their growth in general has slowed quite a bit- there are even a couple spikes that have seemed to almost stop developing. Could this be seasonal as well?