There is nothing in the record saying that the marriage were performed time ago.
You found Natividad' death record. So it's clear that the date in the marriage record is wrong.
Browsing the film's images can be seen that there were very few marriages in that parrish, less than one marriage per month, and that the same priest (Fernando Ortiz) stayed there for many years, from Jan 1846 (Image 101) to Dec 1854 (Image 135).
The best explanation I can think of is this: the priest noticed that that marriage record was missing, he wrote the record on 1848 but he didn't put the actual date of the marriage in the record.