It stretched Stoke's unbeaten league run to seven games and strengthened their grip on fifth place in the Second Division.
Lewington added: "Our problem in the first half was that we got back too far behind the ball and in the end it looked as though we considered a 1-0 defeat good enough."
However, Brentford responded with a more positive second half approach although Lewington admitted: "We created situations rather than chances although overall there were not too many opportunities for either side."
Brentford felt they deserved something from a game of few highlights.
One memorable moment came nine minutes from time when Olafur Gottskalksson brilliantly turned over a ferocious Graham Kavanagh attempt. The Bees' best efforts came either side of the break when home keeper Birkir Kristinsson denied Martin Rowlands and Scott Partridge.