I spoke to a guy who had the same happen to him on his bar. He contacted Hotchkis and, 'long story short, I believe Hotchkis is looking into the fact that some of their bars can't stand the stress put on them when some guys who go up driveways go at an angle.
If you notice whenever lowered rides go up on driveways do it at an angle as to not scrape the bottom of the ride on the driveway. You'll notice that one wheel (in the rear) is pressed in as the otherone hangs down, well apparently this stress at the bolt holes is too much in some instances and that's why they break there. From what this guy told me Hotchkis is working on a new bar that will deal w/ this issue. Again, this is what this guy told me about this. I'll send him a PM to see if he wants too elaborate more on this.