Late 1940's-1950's St-Sixtus Abdij Westvleteren bottle

This Sint-Sixtus Abdij/Westvleteren bottle likely dates to
the late 1940's or early 1950's, and is one of the few I have
seen from Westvleteren with a label.

I have heard different stories behind the origin of the bottle.
There are also two different versions: one with the word
"Abt" in the lower left corner, and the other with "12" with a
degree mark to the upper right of the "12." While the bottle
shown above is slightly torn in the area, it is clearly the 12
and not the "Abt."

This video from Tournée Générale Season 2 Episode 2 shows, at
the 9.30 mark, Brouwerij St. Bernardus Sales and Marketing Manager
Marco Passarella with a number of old St. Bernardus bottles, of which
he says this one is the first ever with a label.

However, the bottle shown here and the third one from the left
in the video both have the Palm tree of St. Sixtus on the label,
rather than the metallic-appearing cross that appears on later
St. Bernardus bottles.

http://www.flickr.com/photos/belgianbeerspecialist/2286217594/in/set-72157603966458566/lightbox/

The photo linked above, which I took, shows the two of the same
bottles on the floor of the old brewery at Westvleteren. So the question
remains: were these bottles brewed and filled at Westvleteren, within the
walls of the abbey, or at the St. Bernardus brewery in Watou?

The website of expert Cyril Pagniez shows Westvleteren labels here
and St. Bernardus labels here

Note that the 1941 Watou/St. Bernardus labels cannot have been
made that year, as the St. Bernardus brewery did not exist until 1946.
The 1941 date must have referred to something else.

If anyone can shed any light or has a definitive answer for this
mystery, please let me know!