look in your swtor folder! if you the file "assets_swtor_main" you do not have to update if you do not have it, check the link and follow instructions http://www.swtor.com/community/showthread.php?p=11786689#edit11786689
theres a 13KB file called "assets_swtor_main.version" in my folder. Patch Version 13, Built on Fri Dec 2 18:51:58 GMTST 2011 seems legit