You could have corrected that. Simply select the post and the entry box will have your text. Simply type the correction and submit it. I don't think typo corrections warrent an update/edited message. However if you do change the content of a post, make sure you leave a note at the bottom of your original message that you did.
DOH! I guess I should read where the post is before I commnet. You can't update SOPW questions unless you are a janitor. Sorry for the wasted bytes! Thanks jeffa for setting me straight.