n00b error for both parties

today at the apple store an "associate in training" was the person that did my whole iphone order. Told him i also needed a white case and a matte screen protector. He got all 3, activated my phone, checked me out and put everything in a bag. I got home, got out the phone, and installed the screen protector. Something was off however. The screen protector covered the speaker on the phone and did not cover the entire black part. Only then did i realize he had sold me the ipod touch screen protector.

Obviously i am going to return to the apple store, but i dont really want to drop $15 on another screen protector. What should i do? Will they replace it with the correct one for free, i know nothing about iphones yet and assumed i was provided with the correct accessory.