high-pitched squeal coming from pass. front wheel

[lemans4.8]

I have had this issue for a while, but it has gotten much worse. On a long road trip (12 hrs.), about 5 hrs into it, the squeal/rattle started to occur. It only happened when I turned left or hit the brakes from a certain speed, but now it does it on highways going straight, until I get on the gas pedal. When I get off the gas pedal, it starts back up. The dealer said it was my inner brake pad being low, but this was 2 months ago and I still have a good amount left on the outer pad and of course, no wear sensor light. Could it be the spindle or something? I really need to figure it out though... car is going out of warranty in 2 months!