I agree with the folks telling you to check the crankarm bolts. I have had the exact same issue that you described and one of the guys I ride with told me to check that. One of the bolts was a bit loose and as soon as I tightened it, creaking stopped completely...so far. I'm going to feel a little bad about trashing my FSA crank for the last couple years if the loose crankarm bolt was the problem.