Do these census records record Mary, wife of Christian? If so, then she died after 1830.

1830 Census, Aleppo Twp., Greene Co., PA176
Grim, Mary
1 male 5-10
1 male 30-40 (all of Christian & Mary’s sons were married by 1830)
1 female 40-50 (Mary should be about 82)

1840 Census, Jackson Twp., Greene Co., PA176
Grim, Mary
1 male 30-40
1 female 70-80 (Mary would be about 82)