I was fixing to cite similar material. The frequently quoted detection times are based off of tests done in the 80's. Recent studies have proven the numbers to be much lower. No way in hell would he have tested positive that much later after smoking only once. I don't care how fat he is. It makes it even more difficult to believe if you consider that he was probably working out a good bit (thus sweating it out) prior to his second test. Either way, if they sent the samples to be tested via gas chromatagrophy, they could see that the levels of concentration would have decreased had he refrained during the time period between the first and second tests.
That was my initial reaction too but then I found this: However, he should have never used it in the first place.
That says 'the last time it is used,' implying that it would have been used prior to that 'last time.' Trust me, I've had to do my homework on piss-tests before. Isolated usage would never turn up that late.