I picked it up working construction when I was younger. Not meant as a sign of disrespect, but as a term of endearment. I don't call her old lady as in "Hey, old lady, make me a sammich" Most of the time its baby or her name. I call my Dad my old man. He never had a problem with it until a couple years ago. I'm only 33 so if I was old, like 50 or something I probably wouldn't use it as she would not receive it the same. J/K guys. Your only as young as you feel.
Oh yeah. It surprises me how this can offend other people it really has nothing to do with, so much. If husband and wife are OK with it why is it your business. If it is meant to be disrespectful and demeaning, by all means step in, be a gentleman and help the little lady. Everybody lives to their own standards. If it doesn't hurt you personally, well, it's like I tell my kids " nobodies perfect and you need to worry about yourself, before getting into somebody else's business" That's my Monday rant and my .01, I think that's all it's worth today.