Mom cuts babies hair without asking

I dropped off my baby at my moms, my husband usually takes care of her since he works night shift but today he was busy. I left her at my moms, I asked her if she was available and she said yes.. when I went to pick her up my baby had bangs.. I didn’t want to over react because she did me the favor to look after her, but I also don’t think what she did was appropriate. She could’ve at least asked before... how do I tell her that what she did was wrong without sounding like I’m conceded or like I’m being a bitch.... would you be mad?