Does loading a bootcamp partition in VMWare fusion affect Time Machine?
After a little more digging, I found a KB article on the VMWare site that indicates that BootCamp partitions sometimes are added to the backup scheme in Time Machine.

This article indicates how to exclude the Virtual Machines from the backup, which is recommended by VMWare since they have their own best practice document for backing up virtual machines.

After updating the settings, the next time Time Machine ran it ignored my BootCamp partition entirely, avoiding the 4.3 GB backup every single hour. Sanity restored!