Makes a lot of sense if our assumptions are correct.
It makes most sense that the vehicles are assigned to a delivery centre based on existing orders and then some stock if they have sent more than required which seems to be the procedure.
That delivery centre then assigns the VIN's to the existing orders and then if there are left overs they match them to new orders.
Some of us, me included, are with delivery centres that simply haven't done this process yet for whatever reason. Given the time of year, the fact that these seem to be smaller centres with fewer staff, complications with GC, etc, etc, it all seems perfectly reasonable as much as I would have liked my VIN earlier and think the communication process could be improved (feedback which I've respectfully provided back to Tesla and received some positive acknowledgement back from them).