"Your account is authorized for the Wrath of the Lich King expansion"

Hello

I've been playing WoW for a month now i play at my Macbook but today when i woke up this error keeps poping up:

https://i.imgur.com/pYdczwv.png


I changed nothing, nothing has been touched.

In the corner it says "Version 3.3.5 (12340) Release Jun 24 2010" just how it should, no problem.

What's going on? I'm very concerned cuz if i have to redownload and reinstall i would need to do a very difficult process to make it work on my Mac all over again.

Please someone know how to fix this?