ansible-pull fails on subsequent runs

for some reason ansible-pull fails after the initial run with

ERROR! Decryption failed on /opt/ansible-edge/group_vars/all/secret.yml

i have some files vaulted and i pass the vault file each time to ansible, but for some reason it looks like it just ignores it after.
if i blow away the destination directory and run it again, it works fine.

my command:
ansible-pull -v --accept-host-key --vault-password-file=/root/.vault -s 5 -C master -d /opt/ansible-edge -i /opt/ansible-edge/hosts -U git@github.com:myuser/myrepo.git