You're exactly right Jim. They weren't concerned with having web gear that 'matched' perfectly in our collections 60 years later!
I have a couple of pieces of web gear made using both the lighter khaki (OD3) and darker green (OD7) on the same item. They're known as 'transitional' by collectors implying they were made after the military decided they wanted things made in the darker green, and the makers were using up their supply of khaki. That's probably the case most often but I have a couple of 'transitional' items made very early. I think it just shows manufactures used whatever material they could acquire and hues probably changed often from different sources and from one batch to another.