There was a thread about this on the Hermes forum a few months back.
In some stores, the policy is to remove the plastic from the bags - seems to be more in Europe than the US. When I bought my B, it had all the plastic in tact. However, another bag had no plastic. Same is true with the piece of felt that they use on the flap. My SA didn't give it to me - I saw it when I was presented with the bag but it was thrown out prior to the bag being re-boxed. All stores and SA's are different and have different policies. The removal of plastic does not necessarily means the bag is used because the store could have done the removal as per their particular policy.