I have done that actually, lol. However, milk has bacteria in it, and that DOES have a very specific timeline. Gear should have nothing but hormone, BA, and oil. I've used gear past the exp. date and saw no difference at all, and i've never known anyone who could tell it was weakened. However, your point is taken, and perhaps you react differently, or had a different brand of gear. I will say, that my homebrew lasts a long-ass time, stuff 3-4 years old is just as strong as when I made it 
