This is probably due to the bookmarklet[1] that just reads the document.title from the page you are posting. It fills in the title automatically in the posting page. It is quite convenient... but often ends up not producing the actual title that is placed on the page. I believe this is the cause for a lot of HN posts not using the article title but the html title instead. And then people complain about the wrong title. And then mods make a call.
