Same here, I guess because when you are writing and you are really into that story your mind doesn't see the mistakes, even if there's little red squiggly lines under it. It can take me a while before I go back and realized I made a mistake or a spelling error etc. I know when I am in a story I don't think about anything else except for I am writing about, especially if it's an intense scene or one you really get into writing and you forget the world around you.