I have a second home where I turn off the water heater each time I'm not there, and start it back up when there. It's an AO Smith, LP that is 3yrs old, but used 20 times a year. Previously, to start it up, I'd go to 'Pilot' press and hold, hit the igniter a couple times and the light would start blinking right away. Lately, I do the same thing but the light will not start blinking until after holding the 'Pilot' button in with pilot light lit, for many minutes. The pilot lights after a couple clicks of the igniter, but again, the light won't start blinking (signaling it's ready to light the burner) for several minutes. What is the issue here? Originally I thought thermopile, but the pilot lights quickly. Is it just warming slowly now? Thanks!