disconnect?

i was playing a game, doing good and suddenly i got a pop-up i was disconnected.
I had some doubts about it since my connection to the internet is pretty fast.
The page was unable to reconnect to the game and i waited a few minutes (it was a 10 min game).. Finally since i use Firefox i opened up another tab back to life chess and back into the game. (the other tab still unable to connect). I found this a bit suspicious, i wondered can other people disconnect my session?.
why couldnt the other tab connect, while a new tab could?