Archive Bits vs. DFS

We have a master DFS share which is backed up to tape. I have just begun monitoring the DFS traffic and THINK that I see something which may explain the lag in replication time which we have been experiencing. Would someone please tell me if I can correct in this supposition?

Does Backup Exec change the archive bit on ALL files that are backed up even if those files were not altered? Also, does that change cause the DFS service to replicate those changes across the network?