Exmark Belt twisted

[kc5dlo]

I was mowing the yard yesterday when a noise started. I shut the machine down to investigate and found the belt that runs from the PTO clutch to the deck was twisted several times between the fixed idler pulley and the deck. That caused the tension pulley to pull up and start rubbing on the frame. I am guessing that is what was making the noise. The belt is also frayed on the edges. I saved the old belt from last winter when I changed all the spindles, belts and pulleys so I can get back to work without any delay.
My question is what caused the belt to twist? My neighbor is speculating that the grass being taller than I normally let it get, put too much load on it and caused the twist. Any ideas?

 

[Xfaxman]

Don't know, I have had them twist in the past, just untwisted and increased the tension a little and kept using the belt.