I don't think it's muscle (not really enough time or weight training to gain *two pounds* of muscle, which is a LOT of muscle) and I also don't think it's fat (two pounds is 7,000 extra calories, which I also doubt!).
I'd guess it's water retention from any number of things )hormones, sodium, muscle repair, etc). Make sure you're eating *enough* calories to maintain your new exercise. You don't list your height and current weight, but I would think 1400-1600, perhaps? You were vague in your description of your menu. Don't eat too much, but don't eat too little, either!
Stick with your current plan and your body will catch up, I promise!