And since I got the magazine out here's a scan of the FAB page on the F-5 feature: (Click to enlarge)
Note that on the leading edges of the fins of the camouflaged aircraft (same areas as in the illustration) the faded dark green colour (FS34079) looks like grey.
Maybe the illustrator thought it was an extra colour???
It's a great photo. Here we can see the SEA scheme. Dark green looks like grey. The illustrator is very wrong.