I think Belichick is a cheater, but if those balls were inflated in a warm locker room and the got real cold, the laws of thermodynamics may have had something to do with it!
Two things refute that theory ... game time temperature at kick-off was 51 degrees, second, the Colts balls were also checked by the officials and all were properly inflated.
It was actually warm that day. Rained in the 2nd half.