Originally Posted by SAB

The front dropouts can creak as you describe. If it goes away everytime you reseat the front wheel (ie: loosen the QR and re-tighten it) that's probably what it is. I have the same deal with my bike, ever since I put new wheels on. I just put a little grease on the front dropouts (inside, outside, and some in the groove) and it keeps the creaking away for a couple of weeks at a time. I've been meaning to try a different brand of QR lever but I haven't gotten around to it and it's a minor annoyance at worst.