Katie,
I think this is something else. I had exported the file, zipped and emailed it to a co-worker earlier in the week with no problem. She was able to confirm the same file size. Sometime during the week, when I tried to send her a revised file, it exploded to 811 meg when I took the same process to export and compress. I would be happy to send you the file (13.5 meg) for you to see if you like.