Ok Joe, great post.
So it's not a incessant issue, but just enough, that after awhile, I'm like, why is it asking for the passcode? (maybe once a week)
And in these cases, I cannot pinpoint why? Can you usually pinpoint it?
AFIK there is no way to know for sure unless it is in response to something you have just done, such as restarting your iPhone
After your post, I would most likely just shrug it off.. and assume normal...and often mysterious..
That is pretty much what I do. Facial recognition has a setting where you have to be LOOKING at the iPhone and not just in view of the facial recognition camera. The idea is, of course, protection against someone holding the iPhone in front of your unconscious(?) face to unlock the iPhone. Unless I have intentionally done something that would trigger a restart or it is an app that does not accept biometric unlocking, I typically ascribe recognition failures to being distracted and looking away not at the iPhone.