Im a S Ontario guy also and have seen this happen frequently. Huge temp swings likely the culprit. Fortunately my 2012 Heartland hasn't had this problem. I did however drop a tool and it penetrated a large area of the floor. My fix was to very very carefully and slowly heat/soften the area with a heat gun and essentially melt the cut back together. I actually can't find the spot now, it was not small. it took a lot of patience, i did retain the floor texture. You are melting the floor back together, so it potentially will be a weak spot going forward. It has survived two seasons so far.