[Android]Magic 2015

Hey everyone, I wanted to try out magic so I downloaded the free magic app on my phone. After doing the tutorial I rated the game 5/5 stars for the amount of effort the devs put into this game. When I returned to the game I got a bunch of booster packs with foils in them. I was wondering if that was a part of the game because it's weird that the dev would give me so many cards for free. I didnt link my google play account to the game so i know it wasn't purchased.