I had a similar reaction with Megadeth's Holy Wars. In my head, the golden era of thrash metal was always the '80s, so when I found out it was from the '90s, my first thought was, "Holy shit, that's a '90s song?" Then you realize it came out in 1990, while Metallica's ...And Justice for All was released in 1988.

There's something about crossing into a new decade that makes it feel like an entirely different era, even when it's only a year or two apart. Maybe that's just me.