New hash comes online every day via a variety of manufacturers and sales. Hence the track record of endless increases in the hashrate since ASICs were released. However, for a period of months a fairly large amount of hash was diverted to crapcoin.This led to two months of rather atypical stability in bitcoin hashrates. It was being pointed to crapcoin faster than new hash was coming on line and so the diff even dropped. Now that it is all being redirected back at btc we have over two months of growth showing up all at once. It makes it appear as if a bunch of new machines all just appeared out of nowhere, but like I said, it is just two months of growth showing up in just a few days. Of course it spikes the hashrate. You could easily end up with a 40% diff increase by the time the dust settles.