I do it often as well. Sometimes I am looking at the wall and realize that I am staring into space. My next thought is "I am staring into space," and it still takes me a few minutes to get back to reality.

I also do it sometimes where I feel like I am a different person viewing the world from the way that person would. Sometimes the person is fictional, sometimes real.

Other times, on really bad days, I realize the day is gone and I can't really remember how I spent my time.