It does raise an interesting debate for sure. In our home, it is not said. My 7 year old will, the rare time say it instead of 'Oh my Gosh' and he is corrected immediately. Now, if he ever let a swear word slip it would be an entirely more severe reaction than simply an immediate correction/reminder. Now, when he does the odd slip to OMG, would I write a note to his teacher...absolutely not. I definitely think Mom has overreacted here.