Horn sounds during FT

[Jay R]

Looking for advice. FT shooter has just received the ball from the official and the horn sounds (just briefly because the timekeeper realizes he should not have sounded it). We ignored the horn. The free thrower bounces the ball a few times and takes his shot and misses. The horn did not sound just as he was getting ready to shoot. The shooter's coach asks for a repeat of the FT. We did not oblige.

If this was to happen again, I think I would blow my whistle as soon as the horn sounds and start the FT over. Is there an official interpretation as to what to do in this situation.

BTW, NCAA rules.