I thought they were all tested after they won?

Marion Jones stripped of Olympic medals :

"“My track coach Trevor Graham provided me with some nutritional supplements,”she said. “He supplied me this for the 1999 and 2000 seasons. In 2001, I noticed a change in how my body felt, how I was able to recover and my strength level. I felt generally weaker in my entire training routine.” Jones later added:
“Looking back in hindsight, red flags should have been raised in my head when he told me not to tell anyone about our workouts or supplementation program. At that time my rationale was, well it makes sense not to give out any information about what we do, why give my competitors any edge.” "

I can kind of see her point....there is a relationship there where you don't question your trainer....you do what your trainer says and trust that they are doing what is best.
Does this excuse her? No, of course not...because we are all responsible for our own actions in the end. Its just too bad that this had to happen to her (if her story is true).
So the question is....if the suppliment used at the time was not on the banned list...could they still take away the medals? And it has to bring into question all the amazing winners of the past, I mean what sorts of things could they be taking that just weren't on the list yet?

Also, if an athlete is taking natural substances and they read on the tests as a banned substance...will this then mean they are banned even though they got it thru a natural source? The same way that poppy seeds will give a false positive for cocaine...you didn't do it, but the test says you did.