The promo website doesn’t say that. It was leaked in Asia but nothing online. Now folks who registered for the offer previously show it in their online accounts with the new expiration date. No need to re-register.
Update: Offer extension doesn’t appear to be automatic for everyone, some folks still see an end date of the promo of July 3. And re-registering for the offer doesn’t appear to be working at the moment, either, though folks seem to be successful calling in. I imagine this should all sort itself out in a few days, the key will be to determine in your online account whether you are in fact registered for the promo with an August 15 end date.