Is it normal to pop my pillow case?

I been doin this since I was little. I rub the material on my pillow case and make a clicking or popping sound with the material. It's very comforting to me. The louder the click the better. It also has to be a stiff pillow for me to do this. I once took a pillow from a hospital cause the pillow had good clicking material. I do this all the time, especially at bedtime when I am winding down. My boyfriend says I even do it in my sleep. I just love rubbing the material in my fingers and make that snapping sound. The louder the better.