As long as the stitches look good, you aren't getting too much lint in the bobbin and feed dog area, and it isn't breaking often, you are probably okay. I don't particularly like the brand that Bernina recommends. I prefer Isacord. It's slick. What I particularly like about it is that if I have to take out something I sewed, it pulls out very nicely. I agree that the person may have been hoping to make a sale.