Was this wrong of me to do this?

i love my dog i wasen't trying to bother him in anyway. but i had my mp3 player listening to a metal song ( so it was loud) and while my dog was asleep i put the right earphone in his ear causing him to first wiggle his ear around ( like he was iritated) and then raised his head up looking at me like ( what was that sound?) i guess he isn't use to music.was this wrong of me?