UPDATE: It looks like the servers were having some problems, because as I was logging into all my characters to get the rested XP started again, they suddenly had rested XP again. Checked a few, including ones I had logged into again and they are back to where they were yesterday.
The day after launch I logged into all my characters to get their rested XP going. Up until yesterday they were all building up rested XP and had about 1/2 of the bar filled. Today they have all reset back to zero rested XP!
Why did you reset this?