I was on my way to work when the bike seemed like it went over some kind of a small dip in the road. Nothing big, very minor. I going probably somewhere between 30 to 40 mph at the time and the handlebars started to move back and forth on their own after going over this minor dip in the road. I slowed down a bit and it corrected itself and I went on. Has anyone else experienced this? I've heard about tank slappers before and I'm wondering if that's what this was.