I have noticed this as well and can't figure out how it happens. The system has them as being posted in the order it displays them with the time stamp, but the order in the database has it in the order it was actually posted.
Sorry reverse that the songs in the database show up with the wrong order but the date stamps are correct. Which is like totally wacky, it is like the server's time is changing or something.
It's been awhile since I've added songs, but it seems like the last song posted has always bumped the previous song. To me it makes sense for the last song you post to be listed first. The next person to post after you, is then listed first. Just my 2 cents.