Am I being petty?

Tonight my best friend, boyfriend, my boyfriends aunt and I were watching a ball tournament. It's like freaking Antarctica outside so I had an extra blanket and my friend borrowed it. It was a blanket I planned to sleep with at her house (because she fails to give me blankets every time I come) and I begged her to not let anyone else use it and to make sure it got back to her house. My boyfriend and I left because we were cold and went back to his house to watch movies until my friend wanted to go home. When I get to her house and ask for my blanket, she informed me that It was in my boyfriends aunts car. I freaked out and got mad about it and she said I was just being petty but her I am yet again freezing in her house because she "doesn't know" where extra blankets are. Am I being petty or do I have a right to be mad?