This is true.  That is why you see so many posts which remain but have been edited by the writer to titles like: "whoops", "delete", and so forth.  Kind of a pain when one erringly posts, inadvertantly double posts, or posts in reply to the wrong post.  However one quickly learns it is just part of the gig.

 BTW, edits by the originator of the post can only be made for a 24 hour period.  After that, the post is "permanent" and can only be deleted or modified with the assistance of the moderator.