Strangest thing. I read this thread a while back and thought "none of that applies to me". Well, yesterday I was out shooting and while flipping through some menues just happened to notice that AFMA was enabled on my camera and the value was -8!
I disabled and set the default value to 0. Just thought I'd mention it. I will keep an eye on it now just to make sure it doesn't happen again, and if it does maybe I'll be able to figure out what caused it.