Thanks for the suggestion, but my gut feeling is that's not it.
TC's usually fail, and then don't work again. That's not the case here. Also, its a heat sensor only, not a visual flame sensor. I'm not sure cleaning it would help.
If it was the TC that shut it down, it would have been because the pilot went out. The burner does not hit the TC. So, my issue is why did the pilot go out. Under normal conditions it fully engulfs the TC.