That wasn't the problem. There have been some people who have gotten the achievement but no item. When you get the item you can activate it but to add it to your account to always use without having to have the potion in your inventory you have to right click on it and select to add it to your account (forget the actual wording now). Anyway, that was not my case. In my case I did not get it at all. Only the achievement. I submitted a ticket and Anet sent me the item in mail. All solved now. Just wanted to say it has happened to a few people but most just submit a ticket.