erisian trubble

I am not Muslim, far from it, but I live in an area with a surprising number of women and girls who wear hijab head coverings. I will often run into them at the grocery, or in the library where they are child wrangling, etc, and notice that their hair is slipping out or their covering has slipped far back. Is is rude for me, as a non-Muslim woman who is likely in shorts and a t-shirt to point this out, or is it likely the woman in question will appreciate it? Is this the cultural equivalent of an exposed bar-strap, or a wardrobe malfunction? Genuinely curious and like to be neighborly, at least in Real Life.

Question for the Christians, kind of a poll.

Which is more important in defining the way that a person should worship the Christian God/Jesus and live as a Christian: the written revelation in the Bible (KJV or other) or revelations made directly to an individual through prayer and communion with God/Jesus? If personal revelations go beyond and/or vary from those given to mankind 2000+ years ago, are they automatically and necessarily "false" revelations?

If you'd be so kind as to add your denomination to the answer, as I know different groups which consider themselves "Christians" would answer this differently.