Derating isn't an issue here, since there are only three current-carrying conductors in the pipe. However, the wire you used is only rated for 95 amps, and they are protected by a 100- amp breaker. to make it legal, you're going to either have to up-size the wire to #3 or down-size the breaker to 90 amp.
BTW, since this is a subpanel, did you make sure to remove the bonding jumper in the subpanel??? Just a thought.