Well, we went out again Saturday and he was just as good!
There's still a lot of fussing and whining when I'm getting ready to leave, but I'm not terribly concerned about that. I'd like to work on it and get to a point where he's completely calm and quiet, just so he doesn't work himself up to a point where it might progress to barking again. But for now, I'm thrilled with the progress.
And we still haven't heard anything, so he must have been quiet Friday and Saturday while we were out. Otherwise, I'm sure I would have heard about it by now.
We picked up a bone and some bully sticks for him to work on while I'm out walking Riley. This will be the only time he gets them. I'm hoping he likes them enough to draw the conclusion that my taking his bratty little brother out of the house means really good things for him.
But at any rate, it's continued progress, so I'm thrilled!