linux - Does anyone know why rsync would keep sending the files over and over again?

I'm trying to using rsync to backup some files, about half a TB. It's now it a state where it keeps sending the same files everytime it runs.

for example:

rsync -av /data/source/* user@host:/data/dest
sending incremental file list
source/file1.txt
source/file2.txt

I then verify those files are copied over... then the next time it runs it does the same thing

rsync -av /data/source/* user@host:/data/dest
sending incremental file list
source/file1.txt
source/file2.txt

any idea why it's getting stuck on these files? I've tried to wipe the whole dest directory out and start over but no luck.

thanks,