It's an odd phenomenon, but one I'd bet is shared by others like me, that no matter how many times I read a post before publishing it, I always notice something that should be changed after it's actually been published. Stranger still is that these must-edits present themselves immediately after the post goes live and are always painfully obvious, even though, before publishing, I may have read over the completed piece 10 times (and this after it's already gone through myriad iterations).
Curiously, the changes usually have nothing to do with grammar, but rather phrasing, tone, transitions, etc. Frequently, post-posting edits involve the title; I'll decide on something and like it beforehand, but after seeing it at the top of my index page I'm often compelled to change it, despite the fact that I mimic the look and feel of my index page when previewing in MarsEdit.
The point I'm trying to make is that it seems my brain can't pick up on these certain things unless I know others are reading the piece. It's almost as if the knowledge that the world has access to it unlocks some other thought process that empowers me to improve(?) it. Weird, I know.