Apple may have been pressed into giving unintentional upgrades to white iPhone 4 owners who need replacements. Claims made by Apple retail staff talking to 9to5 assert that the company is facing a shortage of replacements for 16GB white models and has cleared offering 16GB iPhone 4S units if the store is out of stock. The iPhone 4S would be a refurbished unit, and it might only affect some stores in North America.