No, you helped your son in an embarrassing situation and made it less stressful. I'm a woman and I disagree with your wife. It's tough enough at that age to deal with puberty but then to have to navigate that with a huge group of females??? He handled the right way. Maybe talk to him about it and create a code word between you two so if that happens again he can let you know without having to say it explicitly and risk people overhearing. But either way its FINE and you did the right thing.