Exchange 2013 Retention Policy

I am designing retention policies and tags for my organization. I was testing a 1yr permanent delete tag on an individual mailbox, specifically set to delete items in the default folders(inbox, deleted items etc.) older than 1 yr.  I added the user mailbox to the policy and immediately noticed that it worked and deleted all the items older than one yr. I then removed not only the user mailbox from the policy, but also deleted the tags and policy. I did this back in August. I logged into the mailbox today to begin working on this project again and noticed that the mailbox folders effected by the policy I had created  only contained mail going back 1 yr. (12/3/2013) which means the policy/tags are still in effect even though I removed/deleted then months ago. Is this normal or is this a glitch? I would have expected that once the policy was removed that the mailbox would then only be subject to the default policy or any other active policies. (no other policies exist that would cause the deletion of mail from the mailbox) Basically I want to know if I implement a policy on mailboxes, is it unchangeable or will it simply change when a new policy is created. In which case the policy I tested with was removed and since no new policy was created, the system kept working under the previously set and then deleted policy?