Thanks for the id! Do you see the two squiggly black and white bands that go across the moth's wings? There's one by the back spots and one in front of the front ones. Are these a reliable identification mark for separating L. pertorrida and L. georgii?

...squiggly lines which was one reason why I thought it was more likely to be pertorrida, but I don't know if that's a reliable distinguishing feature. It's not mentioned as such on the Pacific Northwest Website and it's usually very good on distinguishing features:
http://pnwmoths.biol.wwu.edu/browse/family-noctuidae/subfamily-noctuinae/tribe-xylenini/lithophane/lithophane-pertorrida/

Your moth looks pretty old - not sure how much of the yellowish/reddish markings are natural and how much due to loss of scales!

Do you know how old a moth like this lives? I'm seeing some moths this year that are pretty tattered, and I'm also seeing some moths that look spotlessly clean (I assume these are newly fledged). Moths also seem to be pretty particular about when they are active according to time of year and temperature, so do the ones that live longer hibernate somewhere?

....emerge as adults in the fall, hibernate over winter, then emerge again in spring to mate. Lithophanes and Triphosas are examples of species that do that. As far as I know, species that overwinter as adults are in the minority. I'm definitely not an expert in this, but I did read a British study which indicated that only 3% of UK moths overwinter as adults, 40% as caterpillars, 40% as pupae and 17% as eggs. Don't know what the percentages are for North America. I know that Triphosas have been found overwintering in caves, under Highway overpasses or in outbuildings.
Some species are definitely seasonal (may depend on the best time of year for the host plant for caterpillars) and others may have more than one generation per year - that's especially the case with micro moths; plus species that have only one generation per year in the north may have more than one generation further south.

You're right that the brighter, more "pristine"-looking moths are probably newly emerged. They gradually lose scales as they age.