I think you nailed it, Dan. The exercise, and also what you said on my blog: there's not as much conflict in cheeriness. So, in such a short piece, trying to put a story into it, it takes a bit of misery. In any case, this is a very realistic and heartbreaking piece. I did enjoy it and I think your subtlety makes it really shine.
And I agree about conflict being at the heart of these tiny pieces, as well as the larger ones :)