The Food Fairies Like Me!!

So...I am sitting at school in the main corridor just minding my business and feeling a wee bit hungry when something entertaining happens.  Just as I am about to get up and purchase something to nibble on from a vending machine some people go up to it to purchase something.  I happen to overhear one of them say...A6...voila!!  Free food!!  Sure enough the machine is vending a product without inserting any money!  He explains the science behind the mechanics of the machines and how this one has a faulty selection, etc etc...and then they move along.  Well...I am intrigued.  Did it really work every time?  Did he insert money without anyone seeing?  So, I was about to find out....
I walk up to the machine and push, "A6", and wow...the machine indeed starts to dispense a pastry free of charge!!  Well, I am no thief and so as to clear my conscience a little bit I put in a dollar to buy something else legitimately.  So, I select another pastry and as it is being dispensed a coin drops in the change slot??  I put in exact change, so why was I getting money back....I look down and pull out a dollar coin!!!  Another free pastry!!!!  The Food Fairies must like me, a lot! :)