Seasa, I am with the others, GO GET HIM!! I agree that he probably hasn't had the opportunity to bond and settle in to be a calm bird. It will take LOTS of time and patience. Just know that going in, and things will be fine.
As an example, I adopted a 2 1/2 year old cag this summer, I am her third home, and it's been 7 months with me, and she is still settling into her forever home. She is still cautious, and is just now starting to open up more and more as she realizes she is here for good. I think she's still not convinced, due to her past history. She was in her second home for only 5 weeks. :dry: