My money is on repacking the bearings. I was told by a mechanic who used to work for Shimano that it is not a bad idea to take apart and repack new shimano hubs. He was of the view that the hubs, wheels etc have to travel from a tropical Malaysia to North America, and in some cases, some of the grease used in the hub packing could have thinned and seeped out on the trans-pacific journey. And this does not make for a hub that will be at optimum efficiency.
I would thus advise to regrease and repack your hub bearings.
Last edited by Jed19; 03-31-09 at 10:33 AM.