Weight gain from weightlifting; how long?

I'm not opposed to gaining a few pounds - of lean muscle that is. So, now after a year or so of some intense weight training, I am pretty dang cut if I must say so myself (I have trainers asking what i do for my arms!) and my new focus on my back is really showing. And the legs? when the skin falls wayside, they look nice! I've noticed a more cut look in my upper body here lately. So here's the question: will muscle weight gain show up within a week or so or is it a gradual .2 here and there?

I'm just freaking out b/c the scale has been creeping up over the last few weeks. I've eliminated Crystal Light and sugar alcohols drinking plain water only, 90-120g protein, 1500 calories or so daily, 125 carbs max. I exercise intensely 6 days per week; lifting 3 of those and doing cardio pretty much all 6 days.
My clothes are fitting the same. Could it be muscle gain? If so, why all of a sudden?

The scale is such an inaccurate way to measure these sorts of things that it's really hard to know. I would get your body fat % measured. If your body fat % is going down, but your weight is going up, then you are gaining muscle. But, if your body fat percentage is not going down or is even going up, then you have something to worry about.

It is possible 2 add 1-2 pounds a week with a good weight lifting routine...especially in your legs.

Since I started weight training and running, I've put on about 10 pounds. I have to keep telling myself it's ok. I still get freaky though. But you ought to see my quads and arms!!!! grrr