[If you mind spoilers, please scroll away]

So when I played DDLC I didn't really play it straight 'till the game ends. It took me two times to finish the game. So after my first attempt (which I stopped after Yuri stabbed herself) I took a rest from the game, looked at the wiki, and well, played Terraria. So while playing Terraria, Monika's face was flashing randomly in the screen. I was disturbed but I guess it was normal. I died after attempting to kill the Brain Of Chuthulu and after dying you will always get gravestones which says about your death. Now this was COMEPLETELY DIFFERENT; I died and I went back to retrieve my gold and I saw a different message on the tombstone. It says: "Where are you Pitzzadude? Why aren't you back yet?" Then it says at the bottom: -Monika. Creepy right? I thought it's normal. I told my friend to try it out in his PC but nothing happened. Can anyone explain why it happened?