Dominance Issues

When someone wants a library item, we consider it good customer service to not just point them in a direction but to walk them over to the shelves and hand it to them. At least once a day, as I'm making my way around the desk someone will decide to start walking ahead of me and not let me pass--in essence, they try to "follow" me from the front. It never fails that they guess the wrong direction and walk right in front of me, which means I have to find some polite way of dancing around them to get where we need to go.