We reported last month that the Material Design refresh, which first appeared for Gmail on the desktop, is making its way to the mobile apps. It offers a cleaner interface for the email client and ties it in with the overall design theme Google is applying to all of its products. Now, for Android users, it seems the rollout is more widespread. As 9to5Google reports, version 9.1.13 should be rolling out to more users. If you don't have auto update on, you should head to Gmail's Play Store page to see if the update is available for you.