Error 502: Bad Gateway

[thebitcoinquiz.com]

Hey!
While I was trying to open my profile page from the index page of Bitcointalk, I got this Error 502 : Bad Gateway.
It kept on happening till I deleted my cookies and logged in again. After it everything became fine. I have encountered the same situation many times since the forum went down(when RAID failed and theymos had to use backup and all).
What's this? And is this something serious?

[irfan_pak10]

I received the same Message Today, But only today and only for just One time at 12:14 AM +5 GMT. I think its a minor DDOS attack,