2009 Scion tC weird braking noise

When I am going slow (less than 10 mph) and making a hard left turn and braking my brakes seem to shudder. I can hear a noise and feel it through the brake pedal, but it still seems to work OK. Is this a problem…?

Yes, it could be a problem.
Since the car is under warranty, have it evaluated by the dealership’s service dept.

You don’t need a diagnosis, and even if you provide a diagnosis, it will be ignored by them.
Just describe the symptoms, and if possible, take a mechanic along for a ride to demonstrate the problem.

Sound like the ABS kicking in.