Has anyone actually had their wine tested for trace heavy metals after topping up carboys with marbles? After reading some of the threads here about marbles from China, I've developed a little concern. Couple of years back I purchased some clear (and not so clear) glass marbles from the Dollar Store and used them to top off a carboy of Zinfandel. Totally forgot about the marbles until after two years of bulk aging - now I'm concerned. Anyone have any additional thoughts on this?