I think you're backwards on this.Yeah, I think that applies to a number of surprise orders; a rail car needs to be filled, a truck needs to be filled, so they build a few extra cars for the appropriate destinations and include them when they wouldn't normally be included. When I see a base configuration vehicle being delivered at the same time as vehicles with multiple options, that's my go-to explanation.
It would make more sense to hold vehicles for a certain location until you have enough to fill a car carrier or train car, then ship them.