I've noticed, too. Brewer carries 2 different quality 15 class bobbins, and I just ordered the more expensive ones (we're talking pennies difference in price). We've been carrying the cheapest for a few years, and I just don't like them. I'll let you know if I see any difference. You could always go with the generic Bernina bobbins, which are definitely a better quality bobbin. They sew well with other machines, but they don't usually fit the bobbin winder (post hole is a little tighter).