Paint lines on fasteners

Anyone here know what all the paint lines across virtually all the fasteners
on my 2006 Sonata are? Did a human go and check for existence / torque after
the robots got done? Or. did another robot follow up on the first robot, and
the pain proves it looked?

 

In my year's of ownership of Asian-manufactured automobiles, as well as
other products built in the same area, this is normal manufacturing
procedure. It is a QC check on the proper installation (and, torque if
applicable) of each fastener. My very first Honda back in the '70s had
them as well. I've noted the same thing on the 2006 Elantra I bought
last month.