Be grateful you tore up that check. I don't remember if it was on here, or in our local newspaper (its bad when you don't remember where you saw something.
) but i read about a scam like that ---
but I just now looked it up:
ConsumerReports.org - Don't fall for this 'mystery shopper' scam
so from what this article says, that is a scam when they send you the money ahead of time like that.