Ember data root state and isDirty are not consistent

Come to a situation where record.get('isDirty') is true but record.get('currentState.stateName') is root.loaded.saved.

The record has a hasMany relationship to say: options, and each option has suboptions which is an array, after the record is loaded, some suboptions are added to each option, and I believe that is the reason why the record becomes dirty, but I don't understand why the state is still at root.loaded.saved.