So, for some reason, my sister decided to do her coursework in the lounge even though there are two places in the house where you can study and she has her own room. I went into the lounge because my grand piano is in there and I wanted to have a play. My sister then starts moaning at me asking why I have to play when she's doing her coursework in there. I then asked her why she has to be in there when she can literally do her coursework anywhere in the house and I can only play my piano in one room. After saying this she then storms off. Am I the asshole?

Edit: Just to make things clear I did not purposefully go and play the piano because she was in there. I had no idea she was in there until I went in. Sorry for the confusion