Many BTC sites are getting DDOS attacks these days. This is a much greater problem with some pools. Probably it is hackers looking for weaknesses.
BTC sites are being hacked... wordpress sites have massive brute force attacks going on... e-mail accounts are being brute forced... I'm sure there are a ton of other web service being attacked.
Massive, concerted effort to strip the world of btc from accounts with weak/duplicate Username/Passwords??
Watch yourselves out there folks... be smart!
Keep it Clean! 