Sorry Phil, I'm not calling bullsh!t on that one 'cause I've never heard that one before and nothing would surprise me, but I do know that brake fluid is very "hygroscopic" meaning it will absorb moisture easily. You would think that a sealed Brake line system would prevent this but it Does get in, via seals and the porosity of brake components, I believe some fluids are less prone than others, but failing that it may just come down to bleeding the system out more often, which is not a bad thing anyway...,