From the Apple discussion groups, drm31078 says:
Received another reply from synology pointing to Lion as the problem…
Here is what I received from my engineers.
This problem seems to have happened since OSX 10.7.
We use the open source – netatalk to support AFP and
it summarized that this problem also exists on Apple Time Capsule too.
For the Macs that doesn’t trigger “Start New Backup” YET,
users may use the following method to try and fix the verification flag and avoid wiping out all old backup history.
Hey Apple are you seeing this?!?!