2004 Saturn L300 New Brake Noises

I had new brake pads and rotors put in almost 4 months ago. A month after they were installed, though, I noticed a soft, persistent, high-pitched chirping coming from my left front wheel. After paying close attention for a couple weeks, I realized that the wheel doesn't always chirp - it only starts after I've depressed the brakes enough times. I also noticed that when I use the car after letting it sit overnight, there is a persistent metallic scraping sound from the left front wheel that may build into the chirping. That scraping noise is heard as soon as I start driving.

I checked the bearings and found no problems. I checked the pads and found no defects or signs of damage. With that being the case, is this chirping noise something that will go away on its own? Is it something to be expected with new brake jobs (even though the left front wheel is the only one making the noise)? Thank you for your time.