Big Emotions, 3 y/o language skills

Kate is a very smart little girl. She has always spoken well and has a strong vocabulary for her age. She also has very strong emotions (particularly anger). Combine that with a stubborn sense of independence, and there is a recipe for disaster. One day a month or two ago, rather than unleash her wrath upon whatever had stirred her ire, she simply said, "I'm frusserated" (4 syllables). Unfortunately that level of control has yet to be repeated.