Aerial roots shriveling up and drying on my Phal

[Fuzzy]

Hello, I posted last week with newbie phal questions and I learned a lot from your answers and from reading the phal abuse board...thank you all. I realized I was making the mistake of overwatering my phal and I will not do that again. However, since letting the medium dry up a bit, I noticed that all the aerial roots on the phal are shriveling up and quickly dying off, including the several brand new small roots that were growing in. Is it because it's not humid enough here? Could it be because I'm not fertilizing (haven't bought orchid food yet, planning to order now)? If it's a humidity issue, is there anything I can do since it's pretty dry here? Or is it no big deal to let the aerial roots die off as long as the ones in the moss are healthy?

I'm attaching two pictures of the roots for comparison. The first picture is from last week with wet medium that was just watered 2 days before. The second picture is from today and I will be watering this orchid first thing tomorrow morning.