What you're experiencing is not unusual. It's nothing more than water retention. When you work your muscles intensely, your muscle fibers soak up water like a sponge. this is what they are supposed to do. You will also notice some swelling and bloating. Your muscles will release any excess water they don't need once your body has adapted to the new routine.
This really is nothing more than some temporary bloating related to your new strength training routine. Depending on how fast your body adapts, figure a week or two for the swelling to go down.
Are you female ? Ever notice your weight goes up during TOM ? Pants that normally fit comfortably get awfully tight during your menstrual cycle ? Well, this is not different. It's just water retention that will pass in a few days. Nothing to worry about.