There are a couple of things that could have happened. You may have flexed the lock bar, kind of "bowed" a little that would have shortened it just enough to make it the proper length. Or, there could have been a lottle slop in the pivot pin that fell into place when you droped it. I have always slapped the knife aginst the work bench edge down when making a framelock. Just to be sure it was "seated" in the place before final fitting of the lock. This takes some time, and another reason I do not make too many of these. Put it togther, check for lock up, take apart, sand, reassemble, and do it over till it is right. Whew.
Paul