I have a friend who wanted those same bottles for her kids because they were touted to be "the absolute best thing" for a kid who was not breast feeding and she had huge guilt issues over not being able to get the breast feeding thing going with her son.
Long story short, she cussed up one end and down the other with those very same bottles because after a couple of uses they would leak no mater which method of sanitization she used or how she tried putting them together. She was so peeved she dumped them all into the trash and finally took my advice to try the platex ones...She liked these much better...
I will say...for platex, the newer type of playex bottle that does not use the insert is VERY nice...I used those and the original for my twins and I used the original for my oldest...
But NO....you are not alone, this can and does happen with this brand of bottle... ;-)