Not quite the same thing, but I was riding home from work the other day and was merging due to construction. I looked into my rear and saw some old lady a good 100+ feet behind me, but I would have been forced to make a pretty quick stop. Nothing extreme, especially not for me, but I just had this gut feeling that this lady wouldn't be able to stop in time, so I dropped a gear and squeezed up a few more cars. I wasn't all the way to the end of the merge, the lane to my left was still open a bit, I was just trying not to be "that guy" that flies down the merge lane to drop in at the last second. I saw a space, moved in to it, looked in my mirror and was convinced this lady would NOT stop in time, and hopped out right quick, moved up a few cars, and then back in.