Before I start putting the windage tray, oil pickup on and bolt down the oil pan, is the rod that has noticeable blue on it anything to worry about?
That's standard procedure.... heat the small end of the rod to expand it, then push in the wrist pin..
Yep, I've seen it done but I'm keen on spotting differences, aka, one of these is not like the other.
It’s nothing to fret about! Now if the blue coloring continued on down the beam of the rod for another 1” or so then I would be concerned that the tempering of the pin area and rod beam has changed and become more brittle.