It is common for a dog to exhibit dominant behaviour in one or two situations and not in any other.
I have seen dogs that have been competition level obedience animals refusing to allow their owner access to an armchair, for instance.
Many dogs are happy with their position while at home but take the role of Alpha as soon as they step out the door.
Seperation anxiety has become intense by the time destructive behaviour is seen. Sadly this is the first indication to most owners that they have a problem. I have had clients that have even taken the chewing of their possesions and furniture as "normal" dog behaviour and have not asked for help until the dog has started to eliminate in the house or until it has become aggressive!
If your dogs behaviour is becoming less intense and is lasting for shorter periods then progress is being made - you are not fooling yourself!