Two things. I still haven't seen an Apple Watch in real life and I live in New York City and ride the subways meaning I see lots of people in the regular course of my day and probably 50% of them have iPhones. So I'm thinking Apple really had pathetic supplies of the watch at launch. I know Apple won't reveal numbers, but if they had sold and shipped a million by now to the U.S., I think I would have seen one by now.
I have one friend who's wife got the 38mm blue band on April 24 even though he ordered it for his wife on something like April 20. I think Apple realized that the 42mm was going to be vastly more popular, but that they wanted a diverse group of men and women to be wearing the watch around town, so they intentionally did not focus their efforts on the most popular sizes and colors.