[JugglingReferee]

It almost makes you want to ask ahead of time if there are any known problems with the clock.

If issues were known ahead of time, communication could have been made to both teams to be clear that players should play through the horn and only the whistle will inform players that something happened. I would then always have a whistle at the end of quarters.

If you did have the presence of mind to sound the whistle when the horn sounded in your situation above, then all the power to you, imo. But letting it go as described is good, too. We can't be expected to "keep it in our mind" to blow the play dead if there is an IH on an errant device.

As they say, "Fool me once, shame on you. Fool me twice, shame on me". Even if it was before a time where you and your P (Ps) could discuss the matter (such as a TO or quarter- or half-time), I wouldn't let the situation happen again: hammer on that whistle. In football, they say "no cheap fumbles" and I think in this case, the common sense thing is "no cheap plays" especially when a foul and 3-point play is involved.

But what's better is to ask why the horn went off in the first place. When you learn of this errant device, at that time inform both coaches, allow both teams to have a 10-second officials timeout so that the coaches can properly instruct their players, then continue with the game. This is where a good R will step and ensure that everyone is on the same page.