If he didn't pay anything for it and doesn't want anything for it, buy him a beer and say thanks is my suggestion.
As Rich says, you sometimes don't see it until you sand the bat. I've had a few refurbs through the shop recently from well established brands where it's present though, as its sometimes difficult to see. Hadn't caused any damage/weakness, but you never know.
Got a storm damaged G3 I'm using this year too as I wouldn't sell it, but its flying so no detriment in terms of performance.