Oh gosh, I just think regional variation in language is really cool, and while I've heard 'God forbid' a lot in my life, I've never heard the phrase OP used. Turns out it was auto-correct, which I half-suspected, but I would have loved to have known where that had come from. If you're interested in this kind of thing, I highly recommend the talk show "A Way with Words." The hosts get really nerdily excited about just these kinds of phrases, so given that I listened to that program regularly, I'm kind of on the lookout.

Is this also because I'm an atheist living in the South? Possibly. 'God forgot' shows some lack of divine omnipotence, which I find kind of exciting.