"Correct highlighted errors" but there ain't any

I certainly went though a phase where, every time I tried to post, the first time through gave the error message and it was corrected by the second attempt. I got to the point where I assumed the message was a normal part of 'cleaning' any post. I haven't seen it for a while though. Other than it seemed to be more prevalent when cutting and pasting to a message from other sources, I never did pin down the cause.