MOF is not a *sign of distress*... but is a clear indicator that there is... or soon will be, a problem. It goes like this:
Diver 'A' comes to the surface and in their best "Mike Nelson" manner puts their mask on their forehead to relax a bit. Diver 'B'... (hereinafter known as "The Zealot") looks over at them and makes a snarky comment along the lines of "Excuse me... are you in DISTRESS??" (Please note... "The Zealot" apparently is unable to make a determination of the Diver "A's" safety situation by any other evaluative process other than observing that Diver "A" has their mask on their forehead or by asking a direct question.)
At this point, Diver "A" generally says something equally snarky like, "What????"
"The Zealot" then generally repeats their enquiry while cleverly pointing to their own foreheads in order to give Diver "A" a clue as to why the heck they're actually pursuing this rather ordered line of enquiry.
Diver "A" then generally says something cleaver like, "Does it LOOK like I'm in friggin' distress?"
... at this point one of two things occur... either an open water fist fight breaks out (which, while being a really GOOD indicator of distress, is incredibly entertaining)... or Diver "A" figures "The Zealot" is a zealot and proceeds to ignore them to the greatest extent possible... thereby decreasing group awareness on the dive an possibly raising the overall stress and risk level to the group in general...
Voila'... see, its' easy to understand.