Nah, that was me. I put the spawner down and misaligned the floor's blocks to resemble a glitched-up spot to scare you, and apparently I didn't do very well trying to fool you. Oh well! I wanted to clean it up before you did, but I was a little late today.
I assure you, I was being playful, not malicious. The spawner was harmless and didn't seem to work (if it did, it'd have spawned pigs) and I made sure there were no spots for mobs to show up or enter. No paths were blocked, no explosives were laid, it was all in jest, you see. :)
Clearly I didn't convey the glitch joke well at all, so I'm not going to try doing this anymore. I blame
this video for giving me the terrible idea.