Keep Miltonia from getting wrinkles ?

[snowflake311]

How do you keep these plants from getting wrinkles? My new growth is growing well and fast but it has wrinkles. Its a healthy plant good roots I repotted in a few months ago in moss and fine bark mix. It's in a plastic pot. I water it once a week. But I think I should water more because it is growing I have 3 new bulbs going. The humidity in the house averages 40-50% .

The bulbs look great never wrinkle. What is the trick to keeping new growth straight? I feel like I can not over water this plant.