This happens to me sometimes as well, I find that I have to move it a bit in a turning motion to find the right angle to the wall, as what I think is parallel isn’t always actually parallel. The image displayed will tell you that right away, in this case in the upper right corner.
Edit: I made a quick drawing showing what you’re seeing. You should rotate the PPM around its vertical axis (imagine a pole going straight through the middle of the PPM from the top to the bottom of it) a bit to the left (as the distortion is at the right)
