It happened to me, but mine never got to where it locked up. Check the big Jesus bolt under the neck. The locking screw came loose, and the bolt started to back out. As it backs out, the bearings get play, and the rake of the forks forces them crooked, causing them to bind. The steering will get progressively stiffer, but if you're on the highway you may not notice until it gets really bad. I had no idea because I was on a long trip. Once I got on back roads I knew something was wrong. You gotta get the front end off the ground, and tighten that thing back up if it's loose.