Public Service Announcement: check your quill expander bolts or stem clamp bolts.
I was riding home today and was trackstanding at the light when my brakes felt a little funny so I turned the bars the other direction to balance out. It was strange because when the bars were straight I was off balance. I took off and veered to the left almost into oncoming traffic . my bars were not aligned with my wheel! so I turned the bars almost all the way right to get the wheel straight and rode up on the sidewalk where my trusty multitool allowed me to fix the problem.
seriously, check all bolts on your rig at least every couple weeks. its would have been a very different story if it would have come loose while riding at high speeds.