Weard thing happen to me tonight!?

I have a Iphone 3gs and I was playing the app surviving high school ( free version) , I just downloaded it a few days ago so its up to date, and every so often a ad will pop up where you have to hit the "X" button to close it.... and when I did I heard " your so irresponsible,your so irresponsible" sorta in a singing voice!? well i reach up to hit the mute switch.. and it was already muted?... i turn the sound down really quick as to not wake the house up "its was 3:30 am" has this happen to anyone else?... or has my phone gone to the dark side!?