Peristeria Elata care questions (yellowing leaf)

[Spring_Doves]

Hello!

I recently (about three weeks ago) acquired one of my dream orchids, a (very huge) peristeria elata!

I noticed recently that the side of one of the leaves on its newest bulb is starting to yellow. I am aware that this plant tends to lose its leaves as it enters the winter, but, as non of the older growths are yellowing, I began to worry that something is up with the plant. Am I not giving it enough humidity? is it just stressed from shipping? Is it just adjusting to a new environment?

I currently having it growing indoors in sphagnum moss, receiving water when ever the plant approaches dryness. It receives light from a south facing window (that is partially shaded by an oak tree). The humidity of the room is around 50%. Its has been on the rainy and colder side where I live (days have been from 50F-70).

If anyone has any idea of what I could be doing wrong, please let me know!

Thanks!