We obviously grandfathered existing sellers, read what we said :)

3.) Lifetime bonus for existing Minnowbooster customers... limited time offer!
We really want to show existing sellers that we appreciate your loyalty. We want to reward you for being with us from the start so for a limited time you can get the 0.5% bonus but you have to act quickly because this offer only lasts for one week!

Now this is the important part - In order to qualify, existing customers have to sell at least one vote this week in order to receive the lifetime 0.5% bonus - so go ahead and sell a vote right now!