Do you know if they put the 068 signs in setboxes wrapped in paper, or where they always boxed? As common as they are, there should be more 068 boxes. I've seen pristine boxed sets with the sign loose so maybe they did.
Also years ago I had a 253 in dark green with orange windows and die cast lights in a boxed set with regular dark green 610/610/612 cars. At the time I figured they made up the dark green shells with inserts for peacock locos just to get rid of the left over early cars. Then later when they ran out of dark green cars, they buried the dark green locos with orange windows in some of the sets with peacock 607/608 cars. One of those sets is shown in the recent greenberg on page 248.
The 253 set and your set both seem to say they did have stuff in the warehouse.