It's the "Oh shi- there's a boss coming up" theme. I don't remember the name, but it often plays before and/or after a boss battle, especially if there's a item to be won after the battle. Actually, the more I think about it, it's likely only played after a boss is beaten.
@Gary, your music stuff is really great! Also, I think there already was a bit of a music discussion topic in here somewhere, but I guess you could make a new one if you feel it'd be a good idea to start fresh.
@Gary, your music stuff is really great! Also, I think there already was a bit of a music discussion topic in here somewhere, but I guess you could make a new one if you feel it'd be a good idea to start fresh.