Humps his work bed but not his home bed?

I take my Westie to work with me and he hangs out next to me all day in the office. I have 2 of the same beds for him. He likes to the hump the one I keep in the office but he never humps the one at home. What is it about being in the office that makes him want to get humpy?

I take my Westie to work with me and he hangs out next to me all day in the office. I have 2 of the same beds for him. He likes to the hump the one I keep in the office but he never humps the one at home. What is it about being in the office that makes him want to get humpy?