Upgraded iPhoto, now Time Machine backup is huge

Today I upgraded iPhoto from version 8 to 9. After that, the Time Machine backup became huge. Usually the backups are small in size, seemingly little increments covering new documents, email, a few songs, a few pictures. After the upgrade, the backup was 133GB, and wouldn't fit on my backup disk (which is smaller than my Mac HD. Did the iPhoto upgraded do something crazy, like duplicate my photo library or something? Why the giant increase in backup size?

Thanks.

BC