Google has been rolling out updates to Smart Lock over the past months, adding On-body detection and Trusted voice, and while this recent change doesn't bring other options to the table, it does make the feature more user-friendly.

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Previously, if you had set your Android phone or tablet to trust a certain place, Bluetooth device, or any of your physical attributes, it would keep your phone unlocked when those variables were in effect, but you'd still come across a secure lock screen if you left your handset untouched for a period of time. We didn't have any explanation as to the duration of the lock trigger, but that's changing now. A new notification, found in Google Play Service's latest 7.5 update lets you know that the device has been locked and that this happens after 4 hours of inactivity.

This definitely makes Smart Lock more transparent and stops you from having to guess if your trusted settings aren't triggering accurately or if it's simply a timeout that's causing the lock to re-appear.