I think it is a very useful feature although I have seen the same thing cmassa has seen. It is easy to ignore or dismiss, but when it does pop up, I'll take a closer look at the graph to make sure it looks good. Even with a perfect graph and perfect focus, the message is still likely to pop up occasionally if seeing is marginal, causing the validation frame to have a slightly higher HFR than expected. As long as it only happens occasionally, it's not a problem. If it happens every focus run, it is an indication to me that backlash or some other issue is preventing good focus.
Tim