Gander Dog - a very expensive operation!

No, don't get me wrong - I'm not talking about the post-reunion project for the statue in Gander!  I'm sure that that particular project in good hands and will certainly be brought to fruition by the very able team who is now working on it. And I profit from the occasion to wish them loads of luck.

Nope, the expensive project I'm talking about is the "First Day Cover" (FDC) I came across recently.  Given the project and the relation of this dog with the history of early Gander, when I saw it, I knew I had to have it.  So I watched and waited until the last moments of the auction and then put in what I thought would be extremely high bid, enough to shut out the competition. But when I clicked back I found out I wasn't alone!  Someone else had used the same "extremely high bid" theory and was now already at $101, with only a few seconds left.  So I called upon another theory called the "ridiculously high bid" and just managed to squeak in!

The first day of issue is the day on which a postage stamp, postal card or stamped envelope is put on sale, within the country or territory of the stamp-issuing authority. The postmark is always carefully placed so that it can be clearly read. A first day cover (FDC) is an envelope whereupon postage stamps have been cancelled on their first day of issue. 

There are special catalogues for FDCs and usually if one does not have the appropriate one, there is usually some info online about a given FDC. However in this case, even after considerable hours of research, I have found nothing except for one specialist who thought it was fairly rare and issued in very limited quantity. 
So here's the question: Sgt Gander was killed on December 19, 1941 - why would an FDC come out on 16 February 1948?  If anybody has any ideas, please contact me through the web master.

R G Pelley