I installed a new American Standard toilet last November. Ever since I installed it, water continues to drain (you can easily hear it draining) from the bowl for about 30 seconds after the flush is complete and then the "trickling" of water stops. The water level drops a couple of inches and the next time the toilet it used it usally requires two flushes to completely empty the toilet. This is a new toilet but unfortunately I don't have the Lowe's receipt. What could be causing this. Others I've spoke to are telling me that there may be a hairline crack in the bowl that's allowing the water to drain out. Any information on this problem? Thanks in advance for any help.