Well if you're not a regular Amazon shopper then a one day sale would be a surprise.
But if you've been shopping with them for a while and are a compulsive price checker... then this is no surprise. They may drop the price tomorrow or next week, you just don't know.
That's why I ordered my 32gig yesterday with them. They use to have a policy that if the price dropped within 30 days of purchase they would refund you the difference if you called them but they axed that a while ago as it wasn't working for them. Still its tough to beat amazon's prices with no tax and free shipping. I can totally see why major retailers complain about the no tax, it really does hurt them at least with customers like me.