Vermaelen scored both the game's goals.
Wenger told arsenal.com: "I believe he scored unfortunately [at his own end] - left-footed players many times refuse to play with their right foot. But he has shown enough character to come back and score a great goal. On crosses he is very good, he reads the ball well. Overall he had a very good game.
"It's unfortunate to drop two points today because overall I thought we did enough to win it."