I have a 29 Gallon tank on my dresser which is not level - it has been set up like this for probably over a year now. It has never cracked or leaked or anything. If it were to break would it break at the seam or would the glass just crack and break?? The reason I ask is I noticed a line across the front of the tank and I don't know if it is the start of a crack or just a scratch. Please help!!