It's kind of weird though isn't it?
I ordered a 16gb Nexus 5 on monday and they were completely in stock. Checked back the next day and the Play store says out of inventory, rather than giving a wait time or anything?! And because I was worried this would affect my order I've been rechecking the play store religiously and every once in a while the 16gb comes back in stock but then you refresh the page and it goes away again.
Sorry you had to get the more expensive model. Thankfully my nexus 5 is shipping as we speak