Water heater leaking, then stopped.
My 20-year-old 40-gallon gas water heater has always worked fine with no problems until recently it began leaking out of the plastic valve on the side. It leaked slowly for about 3 weeks. At first the leak was maybe a cup per day, increasing to about 3 cups per day. I had a container catching the water and emptied it daily. Then suddenly the drip stopped and it has not leaked for a month.
My question is, why would it leak, get worse, then suddenly stop leaking all-together? And do I need to replace it now or wait until it is working improperly? We have always had plenty of hot water in the house, and no other problems with it.
Thank you!