[shakewell]

Don't put WD040 on your brake rotors. Check your pad wear both front and back - inner and outer. If you're not sure, take it somewhere that will check it for free or cheap. If the noise went away it's probably nothing to worry about. And for the record, squeaky brakes don't mean they need to be replaced - some of the best performing brake pads I've ever used were squeaky from day one.