No other footage from yesterday has the flicker issue so we believe it had to be the over head practicals. I'd love to get back into that location and confirm that they were some old compact florescents or something but that location is long gone for us.
Of course I have seen flicker live at video village when shooting TV's and computer screens etc. But this is the first time I've had flicker only in RGB parade and not visible to the eye. Obviously this has had to have happened before on other shoots but no one in post caught it or bothered to tell me about it.
Thanks for the help fellas. Disaster averted.
From what I hear there is also some pretty sophisticated, but easy and quick, post software now to correct flicker.. but yes best to avoid in the first place of course..