Do the break in procedure again, it will cure it.
Squeak tends to be common for performance brakes ( My father in law has an IS F and they squeak, I am pretty sure they are stoptech too)
When I had the X, they would squeal and I would do the break in procedure and it would clean everything, rematch the pads, and it would quite down.
give it a try
50 mph, brake hard to a stop, immediately back to speed and do it again ( repeat 3 times) then try to drive for 10 min without hitting the brakes to cool them ( the pads will tend to stick if the rotors are hot). you will probably have a nice blue tint to the rotors as well when you a done and they will most likely smoke when you do the 3rd stop :smile:
Justin