Thank you for reporting this to us, Jokoff. I believe this was caused with the rearrangement of the research tree. So that specific expansion was researched by you before it got there. Just a minor side-effect of a game change.
and all other extensions so far, I have normally earned or received by fighting. It is not logical that I would have already received the displayed extension ..
Can you please send in a ticket for that, so that our ingame team can check the amount of expansions you've acquired. Simply right-click anywhere on the game screen and choose 'contact support' from the list.