In the article, the only thing that seems to apply is #10 (below) and reading it this way, makes some sense to me. So, when we get home finally, he is worried that we are going to leave again and can't sleep properly. Double whammy.
10. Separation anxiety keeps a dog from taking advantage of your absence to get in a good nap. During sleep the need to urinate and defecate is suppressed, so the dog can wait a bit longer than at other times. If the dog is anxious, exactly the opposite happens—the stressed body needs to relieve MORE often. A veterinary behavior specialist can help with separation anxiety.
So, I'm going to read up on and talk to people about separation anxiety in dogs. Sorry, no vet behavior specialist for us. Self-instruction and self-informing as usual! There is a trainer around here that I can probably get some info from, although from what I understand she is no longer taking clients.
Edited to add: I just thought of something else. Maybe the night we were back, he left our room to go check on our son and our son's door may have been closed. Then Bandit could have been worried about our son... Hmmm... We are going away again soon for a night. I am going to try to remember to have all the doors open, ensure he goes outside, walk him all around and show him that everyone is home. Then keep all the doors open and cross my fingers.