The penaty was recorded as "Offensive holding" which means it occured AFTER Chicago gained possession, which is why it was enforced from the spot of the foul. That being said, I think it was incorrectly enforced, and was recorded as offensive holding in order to account for the improper enforcement.
And Hester did NOT signal for a fair catch. If he had, no one on the receiving team could advance the ball:
10-2-3(a)3: If a player of the receiving team makes a valid fair-catch signal, and the ball is not
touched by a player of the kicking team, the following apply:
If the ball is caught or recovered by a teammate who did not make a valid fair catch signal, the ball is dead immediately, but it is not a fair catch. The ball will next be put in play by a snap by the receiving team at the dead-ball spot (or at the succeeding spot after enforcement of any applicable penalties).
Basically the same as FED or NCAA in that regard.