I think you're just getting used to it. I did a little research on water a few years ago and I seem to remember that your body will get used to how much water you give it. At first you pee A LOT because it's not used to it and actually has water storage. Then after your body gets used to not having to store the extra stuff (in case you don't feed it water) it then gets used to processing it properly.
At least that how I like to think about it. The research I did was a few years back and at the time made sense to me. I still pee a lot more then most people but I'm kinda used to it now.