If I remember correctly Jesse made Master by finishing above 85% at a major match, which was the Georia state match a few years ago where they had a number of top GMs competing.
From the currect rule book.
Your performance in larger matches and tournaments may also be used to help
establish classification. Placement in a major event with a score above your
assigned class percentage may result in your being promoted to a higher class,
even if your current average is lower. Winning first or second in class at an Area
Championship or Major Tournament AND shooting into the next higher class
may result in promotion (except to Grand Master); winning High Overall in an
Area Championship may promote you to Grand Master class. In addition, if you
score 95% or higher at a USPSA national championship, you will be immediately
moved to Grand Master class for that division.