Feeling of Scare

10 minutes ago I was sitting in the family room working on homework, when my sister Yazmin said that she was going to sleep and she secured that the front door was closed and then she went downstairs. 3 minutes after she left, the door all of a sudden opened and I got this feeling of anxiousness. It felt really weird anyway, I got up and made sure that the door was locked and closed properly, but even though I made sure that the door was closed I still had a feeling of anxiety, so now I am in my room downstairs trying to calm my nerves and writing this post...... Hopefully this accident doesn't happen. :)