Actually I was thinking about this last night, after I posted my last post. I'm not sure how you have your diet plan set up, but if cardio is a big part of it than you might want to watch out.

Training your legs 3-4 times a week while dietng plus if you're doing lots of cardio, especially running, you'll have to be very careful or else you will overtrain your legs big time and lose lots of mass on them.