Moodlets/Quirk Notifications for infants after Infant has aged up

i downloaded an infant from the gallery and started playing it young adult through the cas. after a while it starts to get moodlet about the gassy quirk and becomes sad. after a few seconds it disappears on its own. sometimes it suddenly sits on the floor (just like an infant) and smells like it has a dirty diaper. the save i played has never been used mode before and is new.