Well, since Breezer says the frames are the same, and lighter component builds either don't result in a lighter bike, or result in an actual weight variance less than the sum of the parts, we have to conclude that you have a special, one-off frame that's ligter.

What's interesting, though, is that if such a frame exists, I would have guessed it to be the Sea Otter debut bike Breezer had out there, which had slightly different paint than the MY'12 production frames, and which did not have a head badge. That bike seems to haved showed up on eBay, and been purchased by a BF member. I don't recall if in their thread they mentioned weight, but I would be curious to know.

I don't think of the high tech Taiwanese production process which produces the Venturi as the kind of condition to kick out "one-offs," but given you've verified the weight on two different scales, I can't think of any other explanation...other than that everyone else's scales are off, but that seems even more unlikely, especially since I don't really know anything about Taiwanese bike production.

Anyway, keep enjoying it!