Were my pipes frozen or was my pilot out?
If the heat source is off on the water heater, but no valves were closed, water will still come out of the hot tap. It may even still be warm-ish if you have a tank water heater, depending on how long the water has been in the tank with no heating. If no water is coming out, or water is coming out more slowly than normal, that could be an indication of a frozen pipe (it could be other things, too).