I think if you had actually showed/checked in for the trip, then the leveling would have occurred.

I've been assigned a trip off of reserve in the past worth approx 20+ hours.....had something happen on the 1st leg so that we returned to domicile. Ended up only working about 6 credit hours or so. The leveling, however, remained at the originally assigned trip.

I definitely understand your point based on the contract language. Hope this helps somewhat.