Man, I'd be worried to the point that I'd probably replace all 20 studs. It would bug me until I did.
Whoever thought 5 lugs was better than 6 at Toyota should have to replace these for you. Not that a few percent less load on each can solve a numbnut overtorquing, but losing two of 6 would worry me less.
"Why does the U.S. care which flag will be hoisted on a small piece of land thousands of miles away?" -- Ron Paul