Separation Anxiety

I have not read the book mentioned, nor am I an adoptee. My son was abandoned by his birth family at the age of 8 months. He was hospitalized for respitory problems and birth family never returned. He was put into an orphanage, (he's an international adoptee) where he remained for 2 years. He is now almost 8, he and I have been family for 5 years. We are extremely close and well bonded. He is very close to the extended family - grandma, grandpa, cousins, aunt, uncle. He also bonds to his school teachers to a degree. However, I found out just a few weeks ago that he is not healed from his experience. He went away to camp for a week. He came home and acted as though I was a stranger to him. He felt abdoned the entire time he was at camp, although he had the time of his life. It took him a week to start to be nice to me again, to get back most of his personality. But he is still a little guarded with his emotions of love and caring. He isn't hugging me or kissing me or telling me that he loves me as he did before. We are working on it, that I did come back, I love him, I didn't leave him, I wanted him to enjoy himself. And it's WORK! So, yes those feelings can recur.