Helicopter noise on a 04 honda civic?

I just recently changed my breaks on my 04 honda civic and I did everything correctly. And for some reason when I start driving I hear a helicopter noise and sometimes I don't. Did I do something wrong? Or is there Soemthing else? I also live in Texas and it's really hot if that helps at all.

Check for loose lug nuts.

You did the brake job yourself? What did you do? Changing the brake meaning you only changed the brake pads? That's why. The rotors need to be machined because of the "out of round" problem.

Check for the thickness of the rotors before machine them. If the thickness is beyond the allowance then the rotors need to be replaced.