So the flex mid-corner was in the actual caliper?
I remember seeing some data someone measured on their Evo 8 circuit car with new OE Brembo calipers. When they were brand new the caliper flex (measured with a dial indicator) was ok but it quickly deteriorated over the course of a season of track days.
Edit: Actually disregard that. I have no idea if it was 'ok' to begin with because I have no idea how much is ok. They just got a lot worse with time.