http://us.battle.net/wow/en/forum/topic/2046835986#4
In 4.0.6 an unannounced change landed which removed “Exalted” from anyone who had the original achievement, requiring that a total of 50 reps are now needed.
So, why bother grinding all those reputations to re-aquire a title which had been awarded before?
To be honest I cannot see a reason, in the history of stupid decisions by Blizzard this one appears to be setting a new standard.