Why won't my 3750x stack upgrade automatically?

I received 11 new 3750x switches the other day, and was excited to hear that, with the Stackwise cables installed, I could just upgrade the master to the latest IOS, and it would upgrade all the other switches in the stack automatically. This would save me quite a bit of time and effort versus tftp'ing the ios over to each one individually.

So, like a kid on Christmas morning, I stacked up five of them on the bench, hooked up my laptop to the master, and copied the .bin file over, and waited. And waited. And moved the console cable down to the second switch, and nothing. None of the switches were doing anything. The consultant I had working on my new firewalls said "That should work". But nothing. Tried a couple reloads, still nothing.

Called Cisco and opened a ticket. The TAC tech was very nice, but going on vacation for a couple days. I manually upgraded the first batch of switches, as they were going in that night. Did a bunch of research on the internet while waiting for the TAC to get back to me. Found this article:
Cisco 3750 Stack Upgrade

In the article, I found that for the automatic upgrade to occur, I needed the .tar file, not the .bin file. I downloaded the .tar file, put it in my tftp root folder, and ran this command:
archive download-sw tftp://11.11.11.11/c3750-i5-tar.122-20.SE.tar
then, I watched in amazement as the master upgraded, and then upgraded the other three switches in the stack. It upgraded the boot path for me as well, and deleted the old IOS. Ready to go!

Well, almost.  It seems that once you stack a switch, it remembers it's number. When I went to rack those switches that night, the switch that I brought up third kept insisting that it was number four, and that it was the master. Not good. This meant that interfaces 4/0/1 through 48 would actually be on the third switch, and vice-versa. Two commands fixed my issues here:

To make sure Switch1 is always the master, I set it's priority to 15:
conf t
switch 1 priority 15

To renumber Switch4 to 3, and Switch3 to 4, I renumbered them:
conf t
switch 3 renumber 4
switch 4 renumber 3

Then I reloaded the stack to make all this take effect.
reload

You can also reload specific switches in the stack:
reload slot current slot number

More info here:
Creation and Management of Cisco 3750 Stacks