FS-3 Grid Focusing Screen
Dust specks (red) and a possible misalignment (purple), not sure about the latter; maybe my expectation is higher than Olympus' specification of tolerance.
Using manual focus revealed that the dust specks are trapped between the prism of the viewfinder and the focusing screen: I focused on the focus point border, dust and gridlines are blurry adjusting focus in one direction then gave me focused dust specs and finally focused gridlines.
Update: The body is back from service and the FS-3 has been cleaned (spotless!) and is now aligned perfectly in relation to the focus point markers. I really like the subtle "being there when you need it" appearance of the lines.