Hear and feel 'Click' when applying brakes from 50MPH

Okay, I never experienced this on my Prius C, but now that's I've upgraded to a 2013 Prius Plug-In, I can duplicate it:

When traveling on the highway (at like 60MPG) and I brake a little hard (but not pedal fully to the floor), I hear and feel a 'click' through the brake pedal as it slows through 25MPH. A car pulled out in my lane, and I had to brake suddenly and felt/heard this 'click' at that speed. Did some testing on an off-ramp with the same situation (50MPH - heavy breaking - feel/hear click at 25MPH).

I think this is the transition from the regen braking to the brake pads, but I'm unsure. Not sure if it's ABS either. I've looked at a ton of Gen3 braking threads here on PC, but I was unable to find my exact issue. The car only has 3000 miles on it, so I can ask at my first service - but wanted to see if anyone else experiences this (or if it's normal).

Loving my upgrade so far (but having weird fueling problems - doesn't seem like I can 'fill' the tank, always lose the first 'blip' too fast), and enjoy the freedom of being able to charge for local driving.

Thanks!