I got my answer.
Seems like with the high demand and the upcoming Holidays, they decided to use both kind of arm molds to produce certain sets to complete their production. So apparently, both styles are available out there.
I wasn't told the ratio though, so I don't know which kind of arm is rarer.
As a follow-up, I was also told that the sets produced in 2013 should have the proper sleeves.
I don't know if we can assume that the sets that will be released for the International market will sport the same arms as those seen in the catalog pictures.
We'll see.