In Daytona Beach, Florida, 14-year-old Kaitlin Webster was at her local Wal-Greens store when she came across the precious book.
"I thought it was just a box for display," Kaitlin said in her local paper.
"Then I thought it was a joke."
Her mum said there were only three or four on the shelf.
And a New York newspaper's being sued by JK Rowling after publishing snippets from a copy bought at a health food store.
Again, there were only about four copies and the store owner said he didn't know he wasn't meant to sell them till midnight on Friday.
Melissa and Kaitlin have refused to reveal any secrets in case they spoil it for other Potter fans.