Is it OCD? I don't think so. We all make mistakes and typos occasionally, but it can be confusing and make it hard to read when there are too many glaring errors. Another thing that bugs me is when the wrong word is used because it maybe sounds similar; for example lately I see 'weary' being used when 'wary' is what they mean. Come to think of it, many people even say it wrong.

I know people think it's not that important and when you point it out you're just betting a grammar Nazi, but when you start to learn a bit about how the law and legal system work with regards language to trip you up, you realise that using the English language properly is important.