I love your question - can a broken component become unbroken. Only audiophiles even know what is being asked. Normal people wold say it breaks the conservation of energy principle.
In the realm of the audiophile this is one of those some people hear the effect and other do not type questions. I vote YES, it can happen. It may not be break-in, but most components require a certain amount of time after being turned on to reach thermal equilibrium and optimal audio performance. Also any time you attach or disconnect a cable the sound can change.