I have 1998 S70, just got it recently. It's my first car, yay! Well, here's the problem. There's a slight rattle in the rear passenger side of the car. It soulds like it's coming from the headreast on the passenger side, but it isn't loose. There's nothing loose back there. I even checked the spare in the trunk and that isn't loose. It's a dull sort of rattle, but it's getting annoying. I don't hear it at all on the highway. I don't think it could be the sway bar? Any help would be great.

peace