I think I've got you. The vintage Tamagotchi age whenever they wake up; say you change the clock to an hour where the character is asleep and then to an hour it is awake it will become a year older. It's stupid, I know. That's probably what did it. It doesn't affect how long it'll take to grow, however. The schedule goes like this-
Baby: 61 minutes including 5 minutes as an egg
Child: APPROX 48-49 hours (if hatched before 6 PM); 72-73 hours (if hatched if hatched after 6 PM)
Teen: APPROX 48-49 hours (if hatched before 6 PM); 72-73 hours (if hatched if hatched after 6 PM)