The literal definition of QE, AFAIK, is "injecting money supply into the market." What the Fed is doing here is swapping one risk free asset for another. These are very different. There was a hiccup in the repo market, so the Fed is "buying" extremely short term (e.g., O/N repo) instruments. There is no net injection into the market. In contrast, during actual QE, the Fed was buying across the curve so that actually available interest rates for economic actors were depressed (again across the curve), encouraging economic activity. The effect is VERY different. The effect was supercharged with operation twist but that is another story.