At about 5,000 km I noticed mine (Raven Tour) weren't rotating nearly as much as they used to but now at 6,200 km (and after the second oil change) they are doing it again.
Don't know if the oil change had anything to do with it. I just took a bit more notice of the bike at that time. I might have smeared some grime into the outside of the seals when I was cleaning off the hub hence making them a bit stiffer. Could also have something to do with some recent riding on dusty, dry gravel roads.
Either way it is not a problem and I hardly notice it.
Peter Damm