What people are not addressing is that an A player fouled on the 5 ball. It is tied 3-3
and going to five is tough, especially if a foul means your opponent is now on the hill.
I would not say anything, being that I made a mistake, and paid for it. If my opponent
does the same thing it doesn't matter, now if the score were different, say a race to seven
I see no reason to give a heads up. Play the score. That is the difference in the set. If
you were both on the hill, I don't think many who are advocating telling the incoming
player of his mistake would actually do it. And if you did, and lost it might be your last
time to do it. I lose all the time to mental errors, and learn each time one is made. So
will the opponent who shot the wrong ball.