Apple has announced an exchange program for its 5W European USB power adapters that “may overheat and pose a safety risk.” The affected adapters came with the iPhone 3GS, iPhone 4, and iPhone 4S models shipped from October 2009 to September 2012 in a number of European countries — the full list is included within the announcement. Though the adapters only pose a risk “in rare cases,” the company is voluntarily offering a…