Why did I lose this game?

Maybe there's a rule that if you are disconnected more then 1min. or 2 you lose automatically. Just guessing.

Happened to me a few times. Actually, many times, because my connection always glitches at the wrong times.

I think the intention is to prevent people who are obviously losing from closing the browser when they have twenty minutes left. That said, IMHO, perhaps there should be a "claim win" button, instead of being automatic? So if your connection broke, and your opponent is a nice guy and knows that he's in a losing/unclear position, he'll wait for you to come back instead of clicking it. 

Unless you get online or its fixed in under two minutes, yes.

Time for a cold Beer