I went out to buy some groceries. The store is about 10 minutes away. I went on foot. I didn't realize how I got there, and how I came back home. I was very occupied with my thoughts. I usually create these scenarios in my head and make a dialogue out of it. At some point I believe I was humming noticeably and making some facial expressions as if the scenario and dialogue were real. Is this normal, or I should worry about it?