Narrower petals/sepals on mini-Catts

[Ioana]

Hi all:
I've had a couple of mini-Catts bloom with narrower petals/sepals than in the past. Photos of the same plant, on left in Oct 2017, on right Feb 2018.

I was wondering if this could be due to one of the following:
1- excessive drying (I repotted in a faster draining medium last summer),
2-low humidity (40-45% for the most part, I grow indoors),
3- too much light.. (Den nobile hybrids bloom under the same lights).
4- something else?

No pests as far as I can tell, plants seem healthy, growing and blooming 2 to 3 times a year.

Any thoughts?
Thank you!