Haha...... You found out that yorkies are no dummies
They'll outsmart you sometimes
I found that sometimes if I have chicken for my pups my Zach will run over and sit or lie down next to me before I say anything
This is what you do to transition from treat to positive reinforcement
When you give your pup a treat ... Praise him at the same time
Then a few times make like you have a treat in your hand and when he does the behavior praise him
And after a while you'll see that he will do the behavior just for the praise