Olefin oriental rug curled at edges, why?

This is a first for me, I have cleaned oriental rugs for 3 years now, all fabrics and styles.  I am not new at this, I trained under a master textile cleaner, and am fully certified by the IICRC.  My wife and I bought one from home depot 6 months ago, I had olefin cleaner left in my bottle, so yesterday afternoon I decided to clean the rug on a slower day.

Right away the edges wrinkled in a wave pattern all the way around, maybe 1 ½ to 2 inches high, and finally today they are going down.   While cleaning I used high heat, olefin traffic lane cleaner, and had plenty of vacuum to get the rugs dry in 4 hours max, no over wetting at all.

My only guess was the AC wasn’t running, and the humidity was 68% percent (we had a ton of rain in PA), I now have the AC on and the humidity is back down to 48%

Any idea why the rug wrinkled?  Its 100% synthetic, the backing is as well. 

I checked again, the carpet is 100 olefin, and the tag recomends from Shaw to use hot water extraction