Am I overtraining?

I have been swimming about 5-6 days a week for the last three months. Sometimes I will take 2 days off in a row and other times I will go three on and one off. I typically swim for about an hour and have recently worked my way up to swimming 800yds in 18 minutes after which I slow down a bit and tackle another 600 or 700 yards. I actaully just knocked my stroke count down to 13 last night in a 25 yd pool. :D I always feel excited to go to the pool at night and I feel great when I am done. I have never felt better in my life; admittedly I am only 30 years old. My problem, if you can really call it that, is that my legs tend to be sore every day when I squat down or attempt to lift something heavy. Is this just a result of my continual strive for improvement or do I need to let my legs rest more often? Perhaps I need to swim every day and push even harder?