You know, since Clark's birthday has been guesstimated after his arrival on Earth, some stupid government person (who had to put down the date) might have messed up and used Feb 29, even though that day doesn't exist in 1966. (Maybe the government person was drunk/high/stupid/whatever.)

The only known quantity that moves faster than
light is the office grapevine. (from Nan's fabulous Home series)