In reference to hot water over heating if electric;it could be that your thermostat has pulled away from the tank not allowing your thermostat to detect the proper tank temperature. As long as you have a pressure temperature relief valve (this is your safty device)I wouldn,t worry, just turn your temperature down to prevent scolding : Noticed the last 2 days hot water becomming overly heated. (no change to settings on tank) Is this a bad sign? Only change lately was 3mos ago draining out tank.: Is it electric? If it is, one of the ways an electric water heater can fail is when the contacts in the thermostat weld themselves shut. Maybe yours are sticking a little….just a wild guess. Lots of water heater information on my website.