Isn't it proper riding technique to stagger when you get behind another bike? I stagger but I also keep my distance since I'm not actually with the other person. I also don't usually pull up right beside them at lights and try to have a chat. That has happened to me a couple of times and it was fine but sometimes they talk too much and I'm sitting there thinking, "I can barely hear what you're saying and the light is green. Can we go now?"