All quest exp has been disabled temporarily for a total of one month due to a staff concern about some players rushing from 50 to 60.
Official announcement of this. It should be back on in about a week or two.
Other threads about this:
Nerfing quest exp = super lame
Bring back quest XP for those of us playing at a normal pace.
"We want people to obtain their levels naturally via kills" --Rogean