She believes you're going to sulk. You admit she's right to us. Did you say that to her? Something like, "I can see how you'd think I'd be mad. It's how I used to react, but I'm working on that."
This is a great response, so much better than "No I'm not mad" which will just lead to "yes you ARE" "no I'm NOT" I might also suggest that since you know she's going to think you're mad at times like that, do something to show you're not. After she said "no" you might have hummed to yourself while cooking, or changed the subject with something like "hey, did you read that story about xxx" or whatever. Work on projecting PMA to her all the time.