Why'd you put it back!

On Friday my daughter had tuck, which cost $3, and I sent her with a $5 note.
On Monday before she went to school I asked her for the change, which resulted in this conversation:
Her: "But I already gave you the change!"
Me: "No you didn't"
Her: "Yes I did!"
Me: "No you didn't"
Her: "I did too. I remember it." *rummages in bag*
Me: "No you didn't"
Her, finding the change envelope in her bag: "What did you put it back in my bag for!"