I know that there are stage crew and house staff that sometimes keep a count of the number of times cell phones go off at performances. The most I've heard of was during Billy Crystal's 700 Sundays. At one performance, according to the spot operator, cellphones went off 22 separate times!!!! I have no idea if that's due to lots of people who aren't used to going to theatre or what, but that's outrageous.
I know that lots of actors from Laurence Fishburne to Patrick Stewart to Brian Denehey have all at one time or another stepped out of character and embarassed people who have answered their phones in the middle of a play. I have zero problem with it, especially in serious dramas which tend to be much quieter than musicals and a phone ringing is impossible to ignore (some musicals are so loud you can't even hear cell phones go off). In such cases, while, yes, I suppose we could all pretend not to hear it and the actors could simply go on without incident, the moment is destroyed anyway and you the audience have been jarringly taken out of the world of the play and are reminded loud and clear that you are sitting in a theater in 2006 watching actors perform. If a cell phone goes off repeatedly, the spell is broken (and it's hard to get back) and I think there's nothing wrong with an actor acknowledging what we all are hearing and are aware of anyway and say something. Not to mention such public humiliation may make others in the audience triple check that their own cellphones are shut off.
It's great that Griffiths started the scene over from the very beginning which made it much easier for the audience and his fellow actors regain their concentration and quickly put the interruption behind them. Unfortunately, until theaters install jamming technology, this is going to keep happening all the time.
"What a story........ everything but the bloodhounds snappin' at her rear end." -- Birdie
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"The Devil Be Hittin' Me" -- Whitney