Consider yourselves lucky that you get warning signs - here in SA usually the first you know about being "done" is the expiation notice (infringement) in the mail.

Given that on some of our better bike roads they are now hiding cameras inside wheelie bins and similar dirty tricks, it can be next to impossible to actually identify a camera location.
I know our cameras here (usually mounted in the front passenger seat of a car) can get you coming and going, so if that is the case in NSW, the notices you saw could actually have been for you driving away from the camera, not towards it...
It's been contractors here for quite a while now - apparently more cost effective for the government, not that they are revenue raising at all!
