Google's got some 'splaining to do.
A particularly stupid move on my part over the weekend left the tip of my right index finger sliced open. Not enough to need a trip to the hospital, but enough that I'm reminded of its existence every time my finger drifts across a rough surface. And the cut is just enough to get in the way of unlocking my Nexus 6P the way I typically unlock it, which means I have to shift my finger just a bit to confirm the unlock and move on with the rest of my interaction. No big deal, there's plenty of finger there for the sensor to grab and I've got other fingers stored if it becomes a problem.
Only it shouldn't have been a problem at all, remember? My phone is supposed to be learning as I use it, and I don't think that has been happening.