Hero and I went to PetSmart today, as we do about once a week. He behaved very nicely, and mostly ignored or sniffed politely at other dogs. However, when one German shepherd barked at him, he barked back and tried to lunge forward (to play, but I wasn't taking any chances that the other dog also wanted to play). I yanked him around too sharply, and he clobbered his head against a display, rather hard.
I got him away from the German shepherd, checked to make sure he hadn't hurt himself, and we went on. A while later, I got to talking with a guy, and when he tried to pat Hero, Hero shied back, cringing a little. This is very un-Herolike behavior (ordinarily everyone is his best friend), and I was surprised. I was still more surprised a little later when the cashier offered him a hand, and the very same thing happened. (He loves the cashier, who gives him ridiculous amounts of treats every time we visit the store.)
Once I thought about it from his perspective, however, I was able to figure out why he was acting that way. The incident with the German shepherd happened quite quickly-- probably too quickly for him to understand exactly what had happened. As far as he knew, he was walking through the store, and then something or someone abruptly clobbered him upside the head. Naturally he was a little worried every time someone extended a hand to him after that.
We'll have to go to PetSmart an extra time or two this week, and try to get him over the fear of suddenly being smacked in the head. Poor dumb dog!