Weight gain from swimming???

Just wondering if anyone had experienced this: Started 2nd swimming life in fall 2007 and have been hard at it since. For the first 9 or 10 months, I was just swimming long and slow until I could go no more. I began throwing in some sprint sets after a good 1600 or so for the next few months. During this period, say a year or so, I dropped 40 lbs, from 235 to 195 (I'm 6'3"). Breaking 190 was my goal, though 190 is probably where I should be. Throughout 2009, I could no longer stand the long swims and did more and more sets, 400's, 200's, 100s & 50's between a warm-up 500 and a warm down 500. My goal is 3000 - 3200/day and try to get as close to 16k per week as I can by doing some variation of the sets above. Over the last year of doing this, I've noticed more muscle I think, and my clothes all still fit right, but the scale is alarming me. I'm hovering around - and some weeks over - 200 again. I think I've slipped in my eating habits (definitely did over the holidays), but I was wondering if anyone has seen this before? Are these sprints where I'm constantly trying to improve my times putting muscle on me that are causing me to fret over the weight gain? Or do I just need to stay away from the fridge? Or what? Blue PS> I know all the sites regarding weight loss & swimming, I just want the answers from the horses' mouths. Thanks!