Sure is IMO. Add another 1 or 2 and see if you get similar results. It is possible that your rock was well cured or close to it before you added it. The same thing happened when I started the 20G and I started it over after I saw good parameters after about 2 weeks. It took another week to prove it and make me comfortable. If you get the same thing relatively quickly it will be time to do a water change and start stocking.