I "believe" that if it is the original paint from 1991, and they repaint just a section, it will show a different shade. But, I would guess a good shop would be able to take age into consideration when blending the new paint.
That sucks, good luck I had it happen to one of my cars, from rear quarter panel down the side, they stopped, started again by the door and continued to the front, for no reason
. THis was 2-3 yrs ago