No, you did not gain 2lbs. It's the sodium combined with normal body weight fluctuations. You did not consume 7000 calories, which you would have to have done in order to gain 2lbs.
Our bodies are comprised of mostly water. Depending upon whether you're working out too can contribute to weight fluctuation. Muscles hold on to water to repair themselves after working them.
Keep eating normally and the extra 2lbs will be gone before you know it.