I have had the cover blow off our Class A Southwind after the straps broke. But, we get a lot of winter wind in our area.
Also, I have noticed, even a light wind will cause the cover to billow if the straps are not snug. It's like a sail boat, it catches the wind.
A light wind will pull the cover off if it is not secured.
I've had it happen a few times when I installed the cover and don't immediately secure the straps. (beer break)
Don't get too excited about the cover blowing off, just make the time to secure it properly.
Your cover is not possessed. :)