The weed example is something that happened to a friend of mine. That's within the last 5 years...

In fact, I remember Comey saying something about it too. But the rule as I know it is not having smoked in the last 3 years. While that is probably fine for most people, it does seem to have a bias when you're considering people fresh out of college. Considering that college is frequently where people try weed, along with a lot of other things (not even drugs, just new activities, dress styles, and so on) as they find themselves.