It would interesting to know how these cars were billed. If they were shipped in a baggage car, one would think they were billed as an express shipment. The Grande did haul LCL in baggage cars on passenger trains for a while until the unions stopped it. 3 baggage cars full of bagged cement is not what one would think of as "LCL".
Knowing the Grande, I doubt out of the goodness of thier hearts they would take a SG carload of bagged cement and put it in baggage cars without getting extra $$ to do it.