I'm surprised no one has noticed this yet, but they changed all the job levels required to gain access to a new class. I just got my copy and started playing but what I've noticed is:

The following require lv3 instead of lv2:
Knight -> Monk
Archer -> Thief
White Mage -> Mystic
Black Mage -> Time Mage

The following require lv4 instead of lv3:
Monk - Geomancer
(I'm speculating that this also applies to Lancers/Mediators and Summoners)