Weight Gain: Muscle Size. Help I'm confused.

So I am alittle confused. I recently checked my weight and I have gained around 4.4lbs. I feel bigger in general but I am sure some of it is fat. My body fat is around 10% I reckon.

Anyway I want to be bigger muscular wise, I train the whole body but it's my chest and arms that need the most attention and most want the size increase. The thing is I train and eat good for awhile now and had a increase in my muscle mass but maintained the same weight and reduced alittle body fat.

My friend said weight is not related to the size of your muscles he claimed his weight never changed but the size of his chest and arms got bigger just by him sticking to lifting and over time it happened.

So is me gaining weight a bad thing? am I just adding on fat if what I want is just bigger muscle size?

Today I am 5"9 and 152lbs BF.10% approx.
January 2006, I was 138lbs BF. 13.9% 

You need to do cardio if you aren't doing so, how is your diet?

Today I am 5"9 and 152lbs BF.10% approx.
January 2006, I was 138lbs BF. 13.9% 

 
152 x .1 = 15 lbs fat 137 lbs muscle
138 x .139 = 19 lbs fat 119 lbs muscle
Loss 4 pounds fat
Gain 18 pounds muscle
 
Wake up!  You are losing fat and gaining muscle!
Keep on going!!!

My Journal Gain Muscle - http://www.discussbodybuilding.com/fb.ashx?m=111173 Lose Fat - http://www.discussbodybuilding.com/fb.ashx?m=111175

Of course I do cardio. I know I have gained muscle and lost fat, my question is does having larger arms/chest (size) mean you are going to weigh more? As a friend claimed his weight/fat has never changed yet the size of his chest and arms have got alot bigger.

of course! it's not like you get extra muscle without gaining anything. but yea your friend was probz losing fat as well as gaining muscle, which is why maybe he didn't gain any weight. 

redistribution of bodyweight and holding more water in the muscle making it look bigger...

My Journal Gain Muscle - http://www.discussbodybuilding.com/fb.ashx?m=111173 Lose Fat - http://www.discussbodybuilding.com/fb.ashx?m=111175