It will take a few seconds after a start to register 14V on the cluster...you're fine there.
I also think something is loose or corroded...ground, battery cable, cable under the +terminal under the hood.
But, tell him if the battery light flashes again and increases its frequency until it's on all the time, that he needs to get home right away because he's driving on battery alone.
Upcoming NYC dates: Jan 8 and 27. See Facebook for other shows and PM me if you can make one...love to see you there!
Mangofy your E46!