I spoke to costco, verizon and samsung, and here is what they are saying:
Costco: you can exchange here within 90 days, after that you must go to Samsung. However, there is no call list (first come, first served) and they won't be getting very many in (not all the colors either), because they are a low priority retailer.
Samsung: Verizon is the one who will exchange your phone, not Costco (I think this is bull, but they have told me that 3 separate times).
Ko ko
Verizon: You must exchange at Costco, but if they give you any hassle, go to one of our corporate stores and we will help you. They also told me Samsung has not officially told Verizon about new units coming in.
The good news is that all 3 agreed the BOGO rebate will not be effected.