I am seeing it in the Mike's videos as well, I am about 49 minutes into 03 and his voice was noticeably softer when it went from the talking head to the Logos screen. It isn't as pronounced or as often (IMHO) as in Johnnie's set. If I had to hazard a guess, I would say that it sounded like a different miking set up between the two scenes.
At 54 minutes, it became noticeably louder