I called a hindrance on an opponent in my Friday match. She kept yelling out "short" to warn her partner that I was going to smash her weak lobs. When I called it she flipped, and said "I'm allowed to talk until the ball crosses the net and is on your side of the court." Bzzzz, wrong. I ended up calling it a 'warning' and we played on, even though there are no warnings with hindrances. She would not relent her incorrect position, and we still had a lot of tennis to play. Not worth it for a mixed doubles match.
She did it at least 3 more times that match, albeit quiter (which irked me) but I did not consider it loud enough to hinder. After we won, I showed her partner The Code entry and asked him to inform her on his own time.