There is already some data indicating that Tesla has produced far more cars in Q2 than they ever have in any other quarter before. However, they may not have sold/delivered all of those cars yet. It is entirely possible that Tesla has met their production goals for the quarter but they haven't met their delivered goals.
If that is the case then perhaps they are slowing production down to focus on optimizing the lines for next quarter. They could be cutting costs or increasing efficiency or a little bit of both right now. Meanwhile they are just simply shipping cars to locations that are close by and have a guaranteed sale.
Units produced and units delivered are both metrics that Tesla cares deeply about. From the data I have seen they have blown the units produced metric out of the water. The units delivered remains to be seen.
I imagine that VIN assignments will start again once Q3 has begun. Until then the closer you are to the plant the more likely you are to get a car in June.
My car is said to be delivered in Raleigh NC tomorrow but I have had a VIN for a couple weeks now.