What do I tell the coach?

[lrpalmer3]

A1 shoots and misses a free throw. Before the shot goes up, you as trail and Coach A notice that B1 is standing on the line. He doesn't make a play for the rebound and is ultimately not involved in the play.

Some believe this should be called, others do not. This question is only for those that do not. I repeat, FOR ONLY THOSE THAT NO CALL.....

What do you say when Coach A respectfully asks you if you saw the violation?