A lad I know bought a Macbook online (from Apple ) that came with the clear circle sticker cut and a new one had been put over it , it had a bad drive , it went back .
I know this is a year old thread, but something similar happened to me recently.
I bought the new unibody macbook pro 13. There were two layers of tape on the box, and the one underneath was already open. Bothered me a bit, but decided it wasn't worth an exchange/return.
Few days later, the HD died, and I got a refund.