The issue with your plant's leaf could be 2 things:
1. Underwatering.
2. Rotating the plant too much.
The remedy for rotating the plant too much is simple - know which direction the orchid is growing towards and keep it oriented that way. Technically, there is a back end and a front end, keep the front end towards the light source.
One way to find out which direction the orchid has been pointing towards the longest, is to find where the largest growth is. Face the largest growth towards the light.
Another way to find out is to look at where the orchid is leaning towards. Wherever the orchid is leaning forward, that is the front end.
Yet another way is to look at where the leaves are pointing downwards. If the leaves are pointing downwards in one direction, that is where the front end is.
Plants will usually find the light source and grow towards it.
Whichever reason it is that's causing the leaves to buckle, it's not terribly serious, as you've probably already noticed.