Scaling error in St. Anne's?

Has anyone else noticed that when playing St. Anne's with just the Lieblich Gedact 8' stop, middle C is very noticably softer than the rest? I checked the wave file and it is indeed about 5.6 dB softer than the surrounding notes. Is this an artifact of the organ set, or a real characteristic of the real organ? For my own purposes, I have boosted the volume with Sound Forge and now it produces a very smooth scale.

[mdyde]

It was just the way the original pipe sounded at the time of the recording. I attempted to improve upon some of the more obvious voicing/regulating errors, but I didn't want to make too many changes.

Martin.