I spent a month away from my Time Capsule, and just hooked it up to back up my hard drive on my MBP. Haven't done much the past month except download about 15 songs from iTunes, and mess with a couple word documents. When I went up to the Time Machine icon in the menubar and hit "Back up now" it gave me that box with the option to create a new backup or reuse the backup, which was odd, but I picked the default option of "reuse backup" and then it tried to backup my entire hard drive instead of an incremental back up of just the changes since I last did it. What gives?? FWIW I have a new logic board that I think is garbage since the machine doesn't turn on properly once in a while.