Rotella are second-guessing market expectations..
People who buy quart bottles are ever topping up ere and then, or adding to the stash. The stashers need to know how old it is so they can put it in age order with their other quarts, using the older ones first and the you get ones later.
The gallon buyers are most likely doing a change that day or that weekend, they don't need to know about rotation as they'll most likely fill and forget.