I think it's because there is a sudden burst in the pool. As soon as FTC opened up on BTC-E and saw its value lots of people switched over to FTC mining.
This. The sudden surge in users was unexpected. The stratum issues have been resolved, and AFAIK the longpoll issues have been resolved as well. I'm not running any pushpool miners, so I'm not 100% on this. I'm in IRC if anyone is still having issues.
EDIT: I urge everyone to switch over to stratum if you have not done so already.