Who replaced Cody?

For the last few days, Cody has been quiet and well-behaved. In fact, I was at a meeting for an hour and he just quietly entertained himself without barking. This is clearly not the dog that I had last week.

In general, he's been a lot more mild, so it's not just the lack of barking, but here are my theories:

1. Someone (or aliens) replaced Cody with a look-alike.
2. Cody's sick (don't think so though)
3. Cody's bark collar (which sprays Citronella) is affecting his whole nature. I don't think this is the case because I still can't get the collar to work consistently. Plus, he still barks once in awhile (when he's playing for example).
4. Cody became properly socialized this weekend when he had many "firsts"
1. First trip to a big, "noisy" city (San Francisco)
2. First visit to a huge park (that is more than an acre)
3. First dinner party
4. First trip to a mall (outdoors where dogs are allowed)
5. First meetings with dogs that growl and bark at him (usually he makes friends pretty easily so this was the first time he was scared of other dogs)
6. First time meeting toddlers and babies (he was actually really gentle which was shocking)
5. Cody's learning social etiquette and getting more adjusted

I sure hope it's the last one because it means I'm doing something right. Either way, I just hope it's permanent. I wouldn't want the aliens to bring back the original Cody.