We bought a 2018 Open Range Light 275 RLS and have used it all summer with just a few learning curves. I say this because we have never owned a camper, we tent camped for 30 years. While we were up this past week our fresh water tank filled to full when the lever was in city mode the whole week. On our previous trips this did not happen I was just wondering if anyone could have a answer to why this happened. Thank you for any insight.