Yeah, you'll notice that the sound goes away when you put a little pressure on the brake. What did you use to lubricate them?

Just used some Loctite Anti-Seize that I had lying around - probably not ideal but was all I could find ATT... made sure to fill the rubber boot up as well just to keep the muck out and everything wet...

i had a similar problem (noise), it turned out to be, the caliper slid bolt had come loose on the brakes. rare but better to cross all possibilities off

Just letting you know I had this exact problem on my car but it wasn't the slides it was the pads. I got rid of it by using applying Wurth anti-squeak to the back of the pads and then spraying some copper grease where the pads make contact with the caliper brackets.