Scott McGleish had given Orient the lead when he headed home a Sean Thornton free kick after 17 minutes, and Thornton almost grabbed a point for the home side when he fired a spectacular long-range effort against the woodwork in stoppage time.
Robinson said: "You make substitutions, sometimes they work, sometimes they don't. The manager (Paul Ince) made the decision to bring Sam Baldock off and bring Dean on as he felt he can hold the ball up and play with his back to goal.
"He deserved his goal for all the work he does on the training ground. It is different class and he has carried that on today. It is a pleasure working with him and he has really enjoyed being at this football club."
Robinson also praised goalkeeper Willy Gueret for two crucial saves, adding: "When keepers make such saves you win matches and Willy made two crucial saves."