First of all, be sure they are T218s (Mecca, Hassan or Tolstoi brands) and not T219s (Honest Long Cut, Miners Extra or Red Cross brands). T219s are smaller than T218s:
If you are sure as to which set you have, unfortunately, you probably have some trimmed cards. I've not noticed enough of a discrepancy in height of these cards to catch attention.
Perhaps you could post a scan or two?