Am I wrong to call my girlfriend out on manners?

So my girlfriend doesn't cook, so I do all of the cooking. Which is fine, but I would say only half the time do I even hear her say thank you. When I ask how it is she gives quick deadpan responses like "it's fine". She also looks miserable as she's rating it. I had a talk with her that it bothers me she doesn't always say thank you. She claims that she does & that I don't hear her because she's soft spoken. On Saturday night after having this big talk Friday I cook for her & once again get no thank you. So I got mad at her & told her that even after our conversation I still get no thank you. Once again she claimed she said it but I didn't hear. I told her that her effort isn't good enough then. She should make sure I actually hear her. She stormed off crying & we haven't talked or text in a day. Am I crazy for just asking for basic manners from her?

Am I wrong to call my girlfriend out on manners?
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