I have it set to Auto lock after 1 minute of activity but this can happen sometimes immediately after unlocking with the finger print scanner. Ive only noticed it happening while on my hour train commute but that could just be because that's where I'm using it the most consistently.
I talked to Google support via chat and they suggested booting into safe mode to see if it's a third party app causing the issue. Ive currently been using safe mode for an hour and it has happened but only once when it first rebooted.
Has anyone else experienced this? I've contacted Google support again and will update if they find anything.