What brand valve are you using?
Is it a straight yolk fitting or an "international valve" (ie) a valve with a removeable insert which enables the valve to be used for both yolk and din adapted regulators.?
Faber dos'nt make valves, but they DO sell valves made by San-o-Sub in Italy.There has been NO dimension changes in any of the San-o-Sub range of valves for 09 and no o-ring changes either.
San-o-Sub valves sold by Faber are not branded Faber mind, if you post a Pic of the valve I could tell you if its one of their models.
If its another brand of valve, well dimension changes are possible I guess, but unlikely, few manufacturers will just change these dimensions on an ad-hoc basis, theres just no reason.
I think you probably just have a few incorrectly sized o-rings. Swop a few around and check.