This does not appear to have been reflected in the LJ code. As a result, posts from an area four times the size of Texas are registering with the wrong timestamp.
Correct details of the timezone for the Western Australian region can be found at the following sites, amongst others:
http://www.timeanddate.com/worldclock/city.html?n=196
http://www.microsoft.com/australia/timezone/
http://www.worldtimeserver.com/current_time_in_AU-WA.aspx?city=Perth
http://www.worldtimezone.com/daylight.htm
http://www.world-clock.info/time-in-perth-australia.html