If anything in a wheel hub is going to creak I would expect to be either the spokes or the quick release skewer. Assuming the spokes are all equally tight then I'd suggest lubing the quick release joints and camming surfaces, which are internal in the Shimano skewers, and see if that makes it go away.

And if that doesn't make the creak go away then look farther afield. I once had a squeak or creak that I SWORE was coming from my pedals. It even responded to loading the crank arms by standing and pounding on the arm. So I figured either crank to BB joint or the pedal. Turned out to be the seat post to frame was getting too "dry" from a couple or three years of wet weather commuting. Cleaned and greased the seat tube and post and it was silent as a stone. So the sounds don't always come from where you think....