Brake job and such
 

So I went to the dealer today to get the front Brembos worked on. Cost me $350 parts and labor with the pads costing $185. Funny thing is that they checked the rears and they were down to 22%! The car has 21000 miles on it and shouldn't the rears be replaced every other time the fronts are? Has anyone else experienced similar wear on the Brembos at such an early stage?