Nope. I think Star Piece is incorrect, and was just a typo that's spread to places like Serebii. I get a Star Dust with my Mienshao daily, and my game has not been hacked/ AR'd/ etc.
It's just that it's in BW and not B2W2, you get a Star Piece, and most people just assumed that it was the same in B2W2.
Pinwheel Forest - Bulbapedia - it lists Star Piece for BW and Star Dust for B2W2.