This looks like the index to the marriage record you mention.
"England and Wales Marriage Registration Index, 1837-2005," database, FamilySearch(https://familysearch.org/ark:/61903/1:1:263G-J7K : 13 December 2014), Mary Susan Schultz, 1902; from “England & Wales Marriages, 1837-2005,” database, findmypast (http://www.findmypast.com : 2012); citing 1902, quarter 4, vol. 6A, p. 785, Stroud, Gloucestershire, England, General Register Office, Southport, England.
Have you been able to view a copy of the entry? Who are Mary Ann Burford and James Vick? Why do you suspect Mary Susan may have been married previously? Is it because she would be age 31 at this marriage? Could she have been involved in business, maybe a family business, and therefore delayed her marriage?
Just trying to throw some ideas out there. Any member in Stroud, Gloucestershire able to help? Good luck with your search. -NGP