[ALIBI]

The rules seem to indicate that you must let go (not be in contact with) the trackball sometime before, during or after it crosses the finish line once you do whatever it is you do to get it over and to count it must touch either the floor or another robot before you touch it again.

If the trackball passes over the finish line and whichever robot caused it to go over touches it again after releasing it and before it touches the floor or another robot, it simply is not a Hurdle.