Awake early, with sinus pain. Oh, well: may as well get an early start on the day.
Read early-morning Internets & on-line funny papers, then declare shower time.
Hm. Water's not properly hot. Full-hot setting should be near-scalding; instead, it's Just Right. Ends up being a shorter-then-normal shower as the available water cools rapidly.
Dry off. Get dressed. Turn on stove: yes, gas is present, so it's not a neighborhood gas interruption.
Out to the garage. Water heater's blinky status light is dark. Back indoors: furnace's pilot burner is on. So, not a gas-supply interruption during the night.
Run through restart procedure for water heater. Get blinky pattern that indicates a gas valve fault. Wha'? That thing's practically new; I think I got it just last year, and it was not cheap. Well... turn the temperature setting up where I want it; there's a sound of gas igniting. So far, so good; it remains to be seen whether it'll stay lit, get the tank of water up to temperature, and then regulate.
Maybe it was just a controller glitch. Maybe.
'Twas on a Monday morning the Gas-Man came to call...
Update: There is hot water, and the blinky status is now reporting normal. So... glitch?