Actually, I pulled controls sockless in an area with a lot of cheat grass, and I had much less work to do on my O shoe cleanup than I did during the race wearing socks. Strange.
My guess is the cheat grass took a look at your unsocked feet, and took pity on you--it was just too easy.
Seems to me that cheat grass is at a disadvantage when you have no fabric. It only gets a single shot at your skin, instead of being able to hang in there and go for the extended irritation. When cheat grass is prevalent, you may be best off to run naked.
Well, eastern WA events in late spring / summer may just get more interesting!