Yeah, it's happened before too. In fact, I think all the members of the group get an email asking if they'd like to pay and take over. At least they used to.

I've also been told that it's tricky to remove a group, which means if you want to disband it, you have to manually remove all your members one by one unless you want to potentially subject them to a spammy takeover like has happened here. Removing members from your groups is also a pretty painfully slow process.