I'm not sure what you mean when you say you lube the head. If there is a chance that lube gets to the primers, maybe you can live without it. This update seems to suggest the seating is the culprit, however. Another easy way to check seating depth is to stand the loaded rounds up. High primers will cause the cartridge to rock a bit and lean over.
I guess the next step is to take the failed rounds back to the range and try them again. Hope they fire this time. That would end the suspense.