The golden I used to have did similar things w/her ears/eyes when I approached w/a leash. It was a habit formed from years of me sliding a new collar on with the leash attached. She'd squint and pull her ears back in anticipation of the collar being slid over her head.
The smile? I never got that.
If it's commercially made chocolate, they'd have to eat a lot to get sick. If it's 'real' chocolate, a little amount can be sufficient to really make them sick. Commercial chocolate is a lot of fake stuff.
