Nobody made one about it,so i shall do it :D
As most have already seen: 30 sept 2007 is Asuna's birthday (When she was born) So she just became 6 years old
Hooray for young Asuna^^
Article: http://www.crunchyroll.com/anime-news/2013/09/29-1/sword-art-online-author-reveals-asunas-birthdate: