#1...The ref reviewed the balls something like 2 and a quarter hrs before the game.
#2...The refs don't retain the balls for 2 hrs...they give them to "whoever" has normal oversight...but they remain somewhere on the sideline...
#3...Because of the consistency of the off-base psi inflation, I would think the culprit(s) -- rather than letting the air out of the balls in plain sight of anybody...would simply find a way to "swap them out."
And #3 -- both in the consistency of the psi being reduced to 11 -- along with the number of balls...along with the need to not be obvious about it (a likely swap-out, for example)...shows a triple-angle of nefarious intentionality.
The nfl rulebook says:
The Referee shall be the sole judge as to whether all balls offered for play comply with these specifications. A pump is to be furnished by the home club, and the balls shall remain under the supervision of the Referee until they are delivered to the ball attendant just prior to the start of the game.