Update: 1st: my 2016 AWD GT has NO rear jerk or bump in any stop or red signal. However, I have started noticing a lag when I press gas and I am in D. The car takes a bit of time to wake up and move. Next, assume I am already cruising and need to accelerate and press gas - again a noticeable lag before the car starts reacting. Finally, for acceleration itself, I am having to depress the pedal more than before.
ALL of the above - after dealer reviewed, spoke with Mazda is attributed to how Mazda designed their transmission. It learns driver habits and accordingly tunes itself. In other words, as soon as the dealer performed a ECU reset and everything switched back to default, all lags disappeared. It seems I am a gentle driver, i.e. I don't floor gas pedals, slowly accelerate, etc., etc. and the ECU tuned itself accordingly - all with a priority towards fuel savings.
This is advanced engineering/algorithms. Other cars do the same but in Mazda there's noticeable difference. My only complaint is mileage has actually dropped. For now I am attributing it to cold weather, old engine oil. Let's see..................... now that oil's changed and weather's warmer.