I've discussed Soy Sauce before. In that post, I mentioned the difference between the plastic jug of Pearl River Bridge and the bottle with the same label. The jug soy was saltier. Recently, those labels became consistent and the bottled soy is now rated at the higher sodium level.
I had thought I was just using less than before or my taste was changing, but this is also an explanation.
I don't like the low sodium Kikkoman soy sauce really, though its the easiest to find. My preferences run toward naturally brewed sauces over the forced fermentation sauces. I do like the Amoy First Extract soy sauce and it's only 100 mg more sodium than Pearl River Bridge's old sodium rating. That might become my preference. And I picked up some brewed Lee Kum Kee reduced sodium soy sauce as well to try.
I'll let you know what I end up choosing.