Howler,
I'm not sure that it is that straight forward. I believe that if you buy a loan, and a payment comes in before the purchase settles, then it cancels. Right now (early AM 9/18/2012), loans with the following payment dates are still showing as processing (9/11-although these are stragglers, 9/12,9/13,9/14,9/15,9/16. 9/17). But if you bought a 9/17 loan this morning, the purchase could close by this afternoon. But the payment for it probably won't show up for 2-4 more days. In that case, I don't think the purchase cancels. The notes you have to be worried about buying are the ones that are about to flip from CURRENT to In Grace Period (IGP). Again, for today at 1pm Pacific, loans with payment date 9/11 will flip from CURRENT to IGP. I would be careful when buying those.
Caveat - I have never bought a note on folio, I have only sold notes, so it's harder for me to discern exactly what happens on a cancelled BUY.