I counted at least 28 control points on the brainmask when I loaded the set and my log indicates that freesurfer read 22 control points. I've attached part of the log below.
#@# Intensity Normalization2 Mon Sep 16 19:44:17 EDT 2013 /Users/jonathanposner/Desktop/AdultControls/diffusion_recon/6156/Subject1/mri \n mri_normalize -f /Users/jonathanposner/Desktop/AdultControls/diffusion_recon/6156/Subject1/tmp/control.dat -aseg aseg.mgz -mask brainmask.mgz norm.mgz brain.mgz \n using control points from file /Users/jonathanposner/Desktop/AdultControls/diffusion_recon/6156/Subject1/tmp/control.dat... using segmentation for initial intensity normalization reading from norm.mgz... normalizing image... Reading 22 control points... only using 22 control points from file, mean 84.1, scaling by 1.31... building Voronoi diagram... performing soap bubble smoothing... removing outliers in the aseg WM... 4899 control points removed building Voronoi diagram... performing soap bubble smoothing... building Voronoi diagram... performing soap bubble smoothing... 3d normalization pass 1 of 2 building Voronoi diagram... performing soap bubble smoothing... 3d normalization pass 2 of 2 building Voronoi diagram... performing soap bubble smoothing... writing output to brain.mgz 3D bias adjustment took 4 minutes and 46 seconds. using MR volume brainmask.mgz to mask input volume... white matter peak found at 111 white matter peak found at 102 gm peak at 66 (66), valley at 25 (25) csf peak at 33, setting threshold to 55 white matter peak found at 111 white matter peak found at 110 gm peak at 66 (66), valley at 24 (24) csf peak at 33, setting threshold to 55