[Tom, F&L GoR]

Other vehicle things:
More weight in front/less in rear than usual? (is rear light?)
Same tire compounds front and rear? (are fronts stickier?)
Same brake pads (new?) front and rear? (non OEM pads that heat up more slowly?)
Same shock settings front and rear? (loading the tires at different rates?)
Is there a chance the proportioning valve is disabled? (It's a few minutes to look and bleeding one rear brake)

You've got a well tuned car if you haven't commented that the right front behaves different from the left front. The only other report to date close to rear lockup was someone with race rubber, lots of front weight shift, open runway at an airport, spent all day threshhold braking, and saw it on video.