This is a very cute little story, with a very good moral! You should turn it into a children's novel it would do very well I think.

how cute. do you always listen to your mommy? i know i don't. ha. sorry. good job as always. always nice to know what's going on inside that magical hair.

Cute little story. The voice is done very well, very realistically a child's voice.

Some parts are a little confusing such as "Casey wondered if the big man's nose had grown when he broke his promise and started talking to her. Then she remembered that that was what happened when you lied and Casey knew it hadn't." It's not clear whether Casey is concluding that his nose hadn't grown or he hadn't lied...
In addition, the part where "Casey and puppy didn't see any of this" is a bit unsettling. Why is it tol dto the reader if Casey didn't see it? SInce the story's POV seems to be attached to Casey this one instance of Omniscient third person doesn't go with the rest of the story.

Good job though and keep writing! I hope to see a longer work soon.