Noy all wear is wrong or bad. Break in is wear but we all know and expect this to happen. In fact, IME, the amount of wear is greatest when all is new. With the first use the surface texture smooths out. Even Campy hubs with polished surfaces do this (although to a lesser degree). Some wrenches suggest that one should set a new hub a touch tight in anticipation of this break in wear. I think not. One should set the adjustment as the current condition (and any QR clamping pressure) requires and be willing to revisit the adjustment after a few hundred miles.

So your experience isn't at all surprising. I suggest your hub's loosening up is likely a combo od a few things. Break in wear. Spoke tension stretching the shell. And the likelihood that with lot's of new, well packed, grease you might not have felt a slight initial slop to begin with.

But it all really doesn't matter. One should do the maintenance as needed. Readjust as needed, repack as needed. Just like wheel truing. Andy.