Is it common to bend/ break a new aftermarket Manley hardened pushrod with a new LS7 lifters and new aftermarket springs..... All professionally measured and installed, while doing highway speeds with Automatic trans and 3200 TC, basically 200 miles after the build up, a heads and cam swap and tune? Also, two of the spark plugs gaps were closed on 5 and 7 cylinder?
Is it a fluke, or is There something more to the story? What else do I need to check now so it doesn't happen again.

 

What RPM were you at when it bent/broke?

 

Sounds like you may have had some PTV clearance issues... or in general piston to cylinder head issues.

What's the motor combination?

 

I would check measured install height, check for coil bind..
Sounds like you have experienced some valve float.

 

If you broke a pushrod and slammed spark plugs shut, you have some serious interference going on. I would not run that car again until you pull the heads and inspect for damage to lifters, pistons, and rockers.