Read it in most every hot rod mag growing up. Came out of the mouths of every good mechanic I ever knew and still know. No, I have no clue if the factory did it or not. I was not there. I know I do it and I always will. Every time I have gone back to re torque on steel gaskets, I got a little more on the bolts. Every. Single. Time. So that's enough for me.
This is straight from the SCE gasket site:
"•Do you recommend a re-torque on head gaskets? •All racing and performance head gaskets should be re-torqued. Since many of our customers operate in the extreme conditions of Racing and High Performance, SCE recommends a re-torque in these applications"
It can be found here, about two thirds down the page.
