Right, after a bit more digging, I found this note from Podium Racing
https://www.podiumracing.com/shop/du...ck-hypermotard
It looks like the Hypermotard changed from a 1.25 to 1.0 pitch in 2013 so, despite what the spares catalogue says, maybe the same happened to the 2013 Monster. (Or, as you suggested, perhaps it wasn't an official change but they just used them because they were there.)