From looking at the picture of the head it looks like the machinist ran the CNC to fast leaving a coarse (but uniformed) machined finish or the end mill he was using had a chip in it. Although it could be alot better i doubt that had anything to do with the head gasket failing. As long as the head is true you should be fine. i work at a Machine and MFG shop so i seen stuff like that once in a while.