People who dye to cover gray hair: do you find the gray hair does not take the dye as well as your other hair?

i have some gray strands of hair and i get my hair dyed at a great salon, so i have no doubt about the quality of the dye job. i do find, however, that the gray strands do not take the dye as well as the other hair. the dye seems to not ‘take’ as well to the gray as it does to the other hair. people who get their hair dyed to cover gray: does this happen to you, too?