D.A.
I actually work at a store in infant care and have heard of this. I have had a few mom's say the same things you just have. It is the bottles. I am hoping to call the company when I am at work today to see if they are going to try clearing this up or what is wrong. Unfortunately they are the only wide bpa free bottle at this point other wise there is the evenflo glass or bpa free, dr. browns poly pro, nuby non drip, or the original playtex dropins. As far as the born free I would call the company and make sure they know you are having a problem! If they wont compensate for the error then I would try bringing the nipples back to the store you bought them from.