I'm having an interesting phantom braking experience, although I can't say it's related to any software update. Here goes...
We recently drove from Albuquerque to Tucson, multi-lane interstate all the way, and had maybe 4 phantom issues both ways. Typically just a sudden slow down, only 1 time a dramatic hard braking, always with nothing on the road, nobody in front of me, etc., the usual phantom definition.
Contrast this with a drive I take from my house to a rehearsal studio in Corrales, about 20 miles away. The last 3 miles are on a single-lane road with a lot of curves and a strictly enforced 30mph speed limit. The first couple times I drove there with my 3 I used cruise control to hold my speed limit because the cops in this area will nail you for doing 31, and they are right there waiting for you. And the phantom braking was terrible... almost every curve if there was a car coming the opposite direction, whammo.
Here's the interesting part: The last 3 times I've gone there I've used Auto-pilot and.... not a single incident, even though traffic volume has been the same. I cruise those 3 miles with nary an incident, except yesterday when some jackass pulled out in front of me.
Again, can't say this has anything to do with software update because this happened both before the update and then yesterday. The only thing I can figure is that AP is keeping me squared up in the lane where maybe I'm not such a good job at that myself. But that doesn't explain the phantom events on the Tucson trip.