In my experience, this seems to really ring true. It seems to be that the norm is for spewing to come not too long after friendly interactions!
Now for me personally I always started to get nervous when something good seemed to be going on with xH...just waiting for the other shoe to fall. However I didn't start picking fights with him purposely to try and prove anything or to start building walls up. However I haven't been in crisis mode either.
And you know what? XH told me he would purposely keep an emails where I called him something not so nice (yes I did!) incase he had a "weak" moment when he signed his lease for his apartment.
Whatever... I don't care. MLC or not there is absolutely no acceptable axcuse for anyone to be treated the way these people treat others. I don't care what their issues are at the time, is flat out ABUSE.