a friend of mine always weighs the bags he sells at least 5 times, 3 times out of the bag and two times in the bag, because he says he has people coming back claiming that he shorted them. really its only .2 grams. i wouldn't worry about it. i'm sure he didn't mean to. next time maybe just be like "i was wondering if you could weigh it again, last time it was slightly short." i'm sure he wouldn't mind taking 10 seconds to throw it on the scale again to reweigh.