Overall, the hash rate is increasing pretty quickly at the moment. We only passed 100 PH/s a few days ago and are already pushing 120. Maybe miners buying new or extra hardware just happen to be using other pools? Difficult to say for sure what the cause is, but the effect is welcome either way.
It doesn't worry you that 20PH just pop up in just a couple of days?
Honestly, it would worry me more if the hash rate started fluctuating or going down, but the curve on the graph looks pretty stable and predictable. I'm not quite sure how the hash rate can continue to grow as exponentially as it has, but if nothing else, bitcoin has taught me to expect the unexpected.
