people sometimes make typos when answering a question.
Most Helpful Girl
A couple of reasons, to prevent people from changing things that they said, and to encourage users to be sure of what they post before they send it, to try to prevent "posting regret."
When it comes to questions you can always just add an update... though I know it's sometimes annoying when you notice a typo you made in an answer or comment, and you can't do anything about it. But ultimately some typos don't really matter too much, it happens to all of us.
Anyways, information on the posts you make can always be found in the FAQ, http://www.girlsaskguys.com/faq/posts0