I would actually say it might be root rot, considering you are living in Alaska and it is moss. If you have just moved from a rather dry area to a rather cold and damp one like Alaska, you may be watering it too much, even though it was probably just enough in the previous location. The only way to see is to just excavate some of the moss (i see you are using moss, not my personal choice for a phallie, but if it works for you ) from the roots and check, go right down if you need to. Remember, that moss takes a long time to dry, and phallies like it moist, not wet or damp. I could get away with one watering every few weeks.
The other thing it might be, is the lower leaves may just be spent. It happens frequently, and they just turn brown and drop off very easily with a short gentle tug. This is basically meaning that the plant has decided to suck it dry of any nutritional value and then drops it. Nothing to worry about if that is the case.
And no, i dont think it is getting too much light, in my experience, a phallie starts to look nasty when it is getting only direct sunlight.
But you could try repotting now, but i would leave it a bit longer and repot only as a last resort. If you do repot though, i would either try 1:1 ratio of chopped sphag (you can actually buy compressed blocks-try shaving off the compressed dry sphag with a sharp knife) and medium-course bark, 1:2 ratio of chopped sphag and bark, or straight bark.