I thought about that too, but the game doesn't really run when it is closed, a time is just recorded in the save game files and it calculates how much time has passed according to the current time of the computer. Unless they messed with the game by opening it, it shouldn't have been affected

Usually a battery will only reset the date and time if you switch it to a new one, but who knows what they did, Lol. Make sure to check your date and time Jenny!

I could be completely wrong though!

If you do see that the date and time is not correct, make sure you pause your families and exit the game before correcting it. Time does not pass when the families are paused.