Monnierara Millenium Magic leaf has a yellow stripe

[UsagiGreenPaw]

I'm fairly certain the answer to this is around here somewhere, I just can't seem to find it.

I've had this orchid for about 3 weeks. In that time it has started a flower spike, the old bulb dropped it's leaves, and the plant seemed content.

Sometime in the last few days this little leaf developed a yellow stripe down the middle of it. I'm guessing this is a specific issue since it didn't match my google results for yellowing orchid leaves.
I would think if it the orchid was just losing leaves because that's what plants do, it wouldn't be such a pronounced stripe. Fertilizer issue?
Also I'm unsure the leaves should be curled as they are instead of open and spread out.
The humidity is around 50% and temps are around 70-74 in the daytime and 65-67 at night.
Thank you!