Is it normal that i always roll up my drawstrings on any clothing?

Whenever my hoodie or pajama bottoms have those drawstrings attached to tighten the clothing, I have a bad habit of ALWAYS taking the end of the string and just roll it up all the way, then do it over again. I know you might say that everybody does that when they are bored, but the thing is, I do it non stop until I wear a piece of clothing that don't have drawstrings. Then I end up rolling up a piece of paper or gum wrapper tightly and then back out again. I don't know why I do this...