A few thoughts.
I'm assuming it's a 4runner - which model and year? There have been a number of posts on (Trail/TRD Off Road) KDSS Failures. Apparently that sounds more like a clunk though, but you never know until it's checked.
ABS activation sounds like a winding ratchet spring, buzz, clack, clack, clack. If the ABS controller is going out the ABS will kick in super early and you will feel the pedal goes dead. You will know if this happens, because it's like driving on ice and super freaky. You will be like WTF was that?? This happened on my Tacoma - Note it's not cheap to fix.
If there is a failed or stuck component it will usually pull, shimmy, leak or smell bad. Unless you have those symptoms, it's likely something else.
Brakes don't last any specific mileage. I've had brakes last 10K and 50K. It depends on the material and what you do with them. So 30K miles is not outside the realm of possibilities.
The pads might just be worn unevenly. If they are thinner on one side they can do strange things. This happens for a number of reason.
The pads could just be metal on metal it will make a grinding sound. Occasionally the squeakers break and you won't hear anything. Grooved rotors are usually a sign.
Total shot in the dark here. There could be debris between the pad and rotor. It's unlikely on the 4runner as it's has enough space to let stuff out, but this used to happen to my Audi all the time (freakin precise German engineering). Just for giggles I would power wash the rotors. Just stick it in, through the wheel, and have at it. It could just be some dirt embedded in the pad.