When I trained my first chinchilla I found that each day I worked with him there were usually gradual changes.Sometimes but not often there were days when there were dramatic and usually positive unexpected changes similar to what you describe. In my case Blue stopped squirming and trying to hide when I tried to pet him after two weeks of training him to tolerate being touched. It was such a sudden change I thought there was something wrong. I think you can expect more of this.
