What is wrong with pseudobulbs?

[ALJ]

I have three cattleyas that are showing deformed new growth, right at the time when a leaf is beginning to grow from the pb. However the orchids are just fine. Here's some culture info: I grow indoors, water every weekend, fertilize "weekly, weakly" with a flush once a month. The humidity has ranged from 35-50 F this winter. I use 4 T5 lights (6500K each).

Thanks for your help!