Wife does not want to keep extra milk around

Fellas, am I overreacting? My wife exclusively breast feeds our 1 month old. She refuses to pump extra for emergencies or so she can have break. Recently she left the house and got her nails done and the baby had to cry for 20 minutes or so because they were hungry and she got stuck in traffic. After this I brought up that we need to have at least 1 days worth of breast milk in the freezer at all times. She keeps saying she will but doesn’t and gets hostile when I bring it up. I also mentioned to then maybe keep a formula we were planning to use if she couldn’t breast feed but that started an argument as well. She says she doesn’t need either because she is always here.

I’m not sure if this is some post partum fear of the baby being taken away? I’ve ran out of ways to bring it up. She also has not slept more than 2-3 hours at a time because of this.