I had a carpet at one time that did the same thing, calmed down then got angry and bitey again, from what I've read (someone correct me if I'm wrong) it's just kind of something that can happen with the Australian pythons. Mine calmed down a bit before I rehomed him with one of my friends who still has him, he seems to just have moods at this point. One day he's great the next he's meaner than sin.