You are for sure getting there. If the one pic you showed was pretty much all the whitening you noticed, I wouldn't worry too much about it. Mighta been mites but if it was isolated to just a couple leaves and it didn't spread it was probably just a minor light burn or a damaged stem or could be anything. Now if it spreads,,,,, at this stage of the game I'd do the washing thing. Lots of growers wash every bud as just one stage of the process. Ask Rosebud.