Wheel / Brake Binding Noise

My wife began complaining of a noise from the front left of her car about 4 months ago right after a brake job. Naturally, the car would not make the noise when I would drive it. She typically heard a rumbling/bouncing/clunking when turning left and/or hitting a bump.

The car is a 99 Lexus GS 300. We had the pads and rotors replaced. The replacement rotors were NAPA's most expensive, the pads their mid-level ceramics.

Last night she called me from the road and said the noise had changed and become much more dramatic. I had her park it and my dad and I went down to take a look at it.

We got there and reproduced the noise pretty easily. Moving or stationary, if you turn it to the left there was a loud, metal to metal, scrunking/binding noise. We could tell pretty easily there was nothing wrong with major suspension/steering parts and the noise was definitely off the front left all the way out/at the wheel.

We took the wheel off, hub spun freely, and there was no noise when turned with wheel off. We noticed there was a gap between the rotor and the studs (don't know if there's supposed to be extra room in there or not). In addition, the studs were all "pushed" to one side, in other words there was not an equal gap all around, there were flush one side and off the other. We rapped the rotor a few times and it kind of 'broke loose' and we moved the studs to center and remounted the wheel. The noise now appears gone.

My questions are:
- Is there supposed to be a little gap between rotor/studs?
- Was the noise created be the wheel not being snugged over centered studs?
- Or is there some larger issue at play?

Thanks.