I did not resign this game, but the system says I did.

And I didn't even access LG on my phone, where I'd have doubts that I could have done so by mistake.

http://www.littlegolem.net/jsp/game/game.jsp?gid=1647806

Happened to me too. I resigned a wining game. The opponent gave a big thanks. :D

Could it be someone is hacking the site?

Very possibly, but not necessarily. Previous methods of hacking to force resignations have included malicious in-game messages or malicious private messages (which you didn't even have to read), but there's almost certainly no reason why the malicious payload couldn't be somewhere on the forums. There's an utterly trivial fix, but advice on what to do has fallen on deaf ears repeatedly.

It turns out that every single game I ever lost was due to someone hacking the system and making a bad move for me.  I blame Steven or David J. Bush.