Blizzard says to log out and then back in to ensure an upgrade

I have to admit, this is an odd news bulletin. But Nethaera posted this on the general forums tonight without any promoting from the users.

"To ensure a smooth transition to Wrath of the Lich King, we recommend that players who have newly upgraded their accounts, log into the game and log out completely for a short period of time in order for their account to fully update."

So what does that mean? Does it mean I have to be logged out for the game to update? I would think that would be a "duh" kind of thing. But what I'm taking from it is the following steps:

1. Upgrade Account to Wrath

2. Log in

3. /dance

4. Log out

5. ???

6. Log in and go to Northend
   

My guess is that some internal variables in the game need to be reset upon logging in, and those variables might affect other login processes, so you have to "restart" more or less.

Either way, it's good information that should go out to the masses.