Hi there, really didn't even notice it. We have all seen and done grammar errors a LOT worse than that. And I thank God for spell check and those red lines.
I usually (unless pm) hit preview post the first time and read it good before hitting submit button that helps me catch a lot of stuff. And after you do submit it you will have a little time to edit, there is an edit button that will appear to you on your post but it only stays there so many minutes. Edit it then hit the save button. Hope you like it here.