Is it really that big a deal if it's off by a tiny bit? Like caleb610 said, even the same batch can shift a little, so a perfect match was never guaranteed. Sometimes we stress over details most people would never even notice.
My wife spent two weeks trying to match a paint touch-up for a scratch on the wall. In the end, the sun fades it unevenly anyway. We fixate on these tiny flaws while ignoring the whole room.