My dynasty founder has somehow added a day to her adult stage. She's done nothing but sculpt and go to work, and all of the family's life fruit is in my gardener's inventory pending the first vacation. I just wanted to make sure it's okay to cake her up on the day her birthday should be. Failing that, I've got a save from the day before she failed to age that I can go back to.
(I've got a glut of birthdays coming up, and had made a note of whose birthdays should be when. Everyone else in the household aged appropriately that day, but my founder did not.)