The Royals levelled at 2-2 as Al Habsi dropped a wet and spinning ball against the bar that then rebounded against him and went in. But Jordi Gomez popped up late on to earn the hosts the three points.
Martinez said: "Goalkeepers are exposed to that, they're the last men, and it's just Ali doesn't do that, which is why you're so surprised.
"Minutes before he had the save of the game. Internally as a team you should be there to help your team-mate when he makes a bit of an error, which happens, it's a game of errors and you need to be able to overcome whatever situation comes your way.
"Today we showed that type of performance. In the first half we had a little bit of the feeling of something to lose."