I promise to be extremely nice to my ISA... when I actually get to talk to one.
Anyway, the thing that I found curious about the email is that it says the delay was due to the fact that "In our last round of invitations to Model 3 reservation holders, we received an unusually high volume of orders". I'm skeptical of that explanation that the order rate increased significantly. I would bet that they either overestimated their ability to ramp up the build rate or they accidentally sent out too many invitations to configure.