Nothing strange... Just pure luck and averages...
The network diff is adjusted every 2016 blocks, so that with the current network hashrate, about 6 blocks should be found per hour
on average.
It is possible that one hour, 7,8, or in this case 16 (altough i cannot load the image) blocks are found... IF the time between blocks was less than 10 minutes on average for 2016 blocks, the diff would rise... It's all odds and averages tough.
It is possible there was a jump in hashrate, but in this case, the diff will be adjusted in a maximum of 2016 blocks, so everything returns to normal. It is also possible this was just coincidence.
It IS possible to find 10 blocks in one hour using your CPU, altough the chance is really, really, really, really, really small.
