It may mean the boot just doesn't fit you well. I have the misfortune of having a narrow heel, so finding boots is a major pain in the ass for me. It has nothing to do with sizing, it's just the general fit of the boot. Most boots work well for people with wide feet. For people with narrow feet, it's a bit more difficult. In my experience trying on shit tons of boots, DCs tend to run pretty damn wide.
The only boots I've ever found that fit me well are the Salomon F series. I'm on my 3rd pair of Salomon F22s now.