You were exactly right. I really feel like a moron, because normally I know better, but must have had a major brain toot (I say toot because the more traditional word got censored for some reason). Somehow I accidentally mistaked 2000 for 1/2000 (well more specifically it was 2048), so that when I meant to be taking 1/2000 second exposures, I was actually taking 2000 second exposures. Problem solved, thanks.