Just a Bad Dream?

I had a nightmare as I was laying on the couch trying to take a nap to get ready for work tonight. I don't remember all of the details, but I remember John was being deployed to Afghanistan. He hugged me and walked away from me, stepping through these big double doors. Once inside, right over the threshold, he turned and made eye contact with me as the doors slid shut. I do remember tha panic I felt. I ran to the door, banging at the center where they closed, screaming for him to come back, to not leave me. I woke up crying.
John hugged me and asked why I was crying. I told him. His response was that it is going to happen. When this didn't help any, he just smiled and held me tighter, saying "But I will be right back to you!"
I am so scared for us.