Pavlov's coffee grinder

Denny reminded me to write about the coffee grinder.
Every morning, after his walk, I give Zorro his breakfast. Then I put the beans in the coffee grinder and turn it on. This causes Zorro to bark a couple of times. Then he runs to his dog bowl and eats all of his food.
This reaction is so predictable that on a couple of occasions when I wasn't making coffee but wanted him to finish his food, I turned on the grinder. Worked every time.
We have wondered whether this goes back to his time in the shelter: maybe someone rang a buzzer before bringing in the dogs' meals.
Somewhat of a setback yesterday afternoon: when Denny took Zorro out for a walk, he saw someone walking two dogs and completely lost it. Went into his crouch, then leapt at the dogs so intensely that Denny could hardly control him. That was a disappointment because I thought he was getting better around other dogs. Maybe two looks like a herd to him. But if this continues, we'll have to go back to the Gentle Leader collar, which he doesn't like but offers better control.
Brief fireworks last night which caused him to run around the house but they ended early and Zorro was quiet all night. The moon rises very late now, which helps. Did Day 2 of the Protocols; he was a little more distracted last night (probably because of his earlier encounter with the dogs) but we got through all of the exercises, which included running in place, clapping, and feeling slightly ridiculous.