It happens more often than youd think. Of the 10 tournies I've fished in the last year, I've weighed about half a dozen fish caught on minnows, and probably caught 20 out of the last 1500-2000ish I've caught, on minnows. I've watched them nose up to them on Livescope and the minnow would wiggle trying to get away, and spook the fish off, or the fish would back off and lose interest.
I'm not sure why it happens but it does.