time added to opponents clock ?

 my opponenet was down to 9 seconds and then all of a sudden he had 40 seconds !! i sacrificed some pieces for time that i would not ordinarily have done if not for the time that was about to expire. so with the additional time my opponent had the upper hand. i had almost 4 minutes left and left the board to ask the chess master but accidentally left the game. frustrating to lose this way !

note i was told earlier by grandmaster that the site doesnt add disconnect time back on...as i questioned why i timed out after a disconnect without getting the time back. so ?

What you are seeing is due to internet lag. For more information on this, please see these pages in the help section: 

http://support.chess.com/Knowledgebase/Article/View/121/13/what-is-lag-and-what-are-the-colored-lag-indicators-in-live-chess

and

http://support.chess.com/Knowledgebase/Article/View/91/13/why-did-the-clock-times-suddenly-change-the-clocks-seem-broken