Any chance the pdf file was up early and they simply guessed the URL? This announcement was named 20140220-Announcement.pdf (https://www.mtgox.com/img/pdf/20140220-Announcement.pdf) while the previous one was 20140217-Announcement.pdf (https://www.mtgox.com/img/pdf/20140217-Announcement.pdf).

Try it the next few days.