I've had these unvented gas logs for about five years. Same room, same
fireplace.
I re-lit the pilot light this fall. It burned fine. One night my wife lit the
logs. The next day we noticed the pilot light was off. I accused her of turning
the shut off too far and turning off the pilot light.
One evening I told her I will turn the logs off. I shut them off, the pilot
light stayed on. For a few minutes.
So I re-lit it and it stayed on, no problem. Until the next time the logs were
used. After they were turned off, the pilot light burned for a few minutes, and
went off. I re-lit it, it's still burning, but I know that the next time when
the logs are used, the pilot light will go off again.
What can be causing this? About the only thing that can be replaced is the
thermo couple. And if this is defective, the pilot light should never stay on.