How to show that a form has been dirtied (edited) using a Material design?

I have a vertical list of expansion panels. Each panel has a form under it. I would like to know the best style for showing that the form has been dirtied (edited) on the expansion panel title. The goal is to allow the user to know at a glance what has been modified without having to open all the panels. I looked through the Material design guide but didn't see anything about change labeling on forms. I had thought about using italics, bold or adding an asterisk after the title, but figured I'd ask if there was an official way to show this.