To add to this I've just deployed DLP to a new client and it has picked up this very same policy even though it was modified on the 18/11!
If another new deployment received the same policy revision then it sounds more likely that it is a server side issue and/or policy issue and not necessarily a policy enforcement problem. If you go to the following page does it show pending changes?
Menu > Data Protection > DLP Policy Manager > Policy Assignment (tab)
If yes, go to actions > Apply selected policies > Select your policy > Apply policy
If no, try creating a new policy and use your same rule set from your previous policy. Assign the new policy to your system and see if it picks up the new policy correctly.