too quick a learner

I was at the post office last week with Chloe.  I had her and my open wallet in one arm and a package to mail in the other.  The cashier weighed my package and told me my total.  Before I knew it, Chloe had slid my credit card out and handed it to the cashier with a "he ya go!" The cashier was impressed and stated, "wow, you taught her young!"