How was it advertised? A sign at the check-in counter? I fly EVA all the time out of LAX and very often out of BKK too. I can't say I have ever seen them openly advertising upgrades like that. Not that I have ever asked, but if there was prominent advertising that was very unusual and is not the norm. My recent experience has been that most EVA flights out of LAX are very full lately anyway so if it worked that would be nice but I would not count on it.