I just found out my son has been listening to his mp3 during cl?

Just today I was just going to hang-up m sons hoodie when I noticed an object hanging out of one of the sleeves. It was an ear bud. I wondered where it was from so I unzipped it and found that it led to his mp3, which he duck-tapped to the hoodie (near his ribs) and slid the ear buds up the sleeves. I asked him about it and he admitted he was listening to it and rested his head on his ears in cl pretending to listen. What should I do about this? He seems to be having good grades, they aren't any differen't than his last report card. Should I take it away?