BERLIN - Amir Hekmati, one of the Americans freed in a prisoner swap with Iran, said he did not believe until the very last moment that he would be let go and he celebrated with champagne once the Swiss plane flying him out left Iranian air space.Hekmati, who was detained in August 2011 while visiting family in Iran, told reporters outside a US military hospital in Landstuhl, Germany on Tuesday that he felt "very lucky" to be free again."It was very nerve-wracking. I was worried that maybe the Iranian side was going to make new demands in the last minute or that the deal wasn't going to work out," he said.Hekmati was released at the weekend along with four other Americans in a deal negotiated between Washington and Iran.The prisoner swap followed the lifting of most international sanctions against Iran under a deal to curb its nuclear program."This is all so surreal and we're just soaking it all in right now," Hekmati said, adding his release had come as a surprise. "I was at a point where I had just sort of accepted the fact that I was going to be spending ten years in prison, so this was a surprise and I feel extremely blessed to see my government do so much for me," he said.A Swiss plane took Hekmati along with Jason Rezaian, the Washington Post's Tehran bureau chief and Saeed Abedini, a pastor from Idaho, as well as some family members, from Tehran to Geneva on Sunday."As soon as we got out of Iranian air space the champagne bottles were popped," he said, adding that the Swiss served them veal and chocolates.After arriving in Geneva, they three left for a US military base in Germany where they have been undergoing medical evaluations.Hekmati has seen his sister and brother-in-law and said he hopes to return home soon to be reunited with the rest of his family.