death date of mary griswold phelps

The death date of mary griswold phelps, spouse timothy phelps, is often reported to be 11-27-1715 at Windsor, CT.
However, I cannot reconcile this death date with the date of the execution of Timothy's will 3-2-1717 proved 9-28-1719 in which he names his wife mary as one of the persons who receives a portion of his estate. Mary was alive at least when the will was written. Can anyone explain this inconsistency?