15 lbs

When I started to get myself back in shape a little over a year ago my goal weight was 155.  I was ripped at that weight and it took me about 5-6 months to go from a fat 188 down to 155.  I have been avoiding the scale as much as possible since I hit my goal weight.   I got on the scale this morning and I'm just under 172.  Is it possible I gained 15 lbs of muscle in the past 6 months from kettlebell swings, cleans, presses, getups and pullups?  Not only is it possible but I believe it to be fact.  15 lbs is ALOT of muscle to gain at my age in less than a year.  I can not wait to see what the next 12 months have in store for me.