One can never tell the difference between the dream world and real life whilst dreaming, even when you are lucid dreaming the dream world still seems so real. Then again the definition of reality is a debated topic. All things in my imagination are real, at least to me. They can even alter the way I feel- it doesn't mean it is real on a physical level, or to other people.
In other words I do not think you traveled to a parallel universe.