Thank you very much for the response. Cutting back just the yellowing portion was my initial instinct, but since I am new to Orchids (and growing in general) I can't seem to stop second guessing myself.
Also, in my attempt to learn more about general care, I have been doing a lot of reading about diseases, viruses, fungi, etc. The unfortunate side effect is that I now think any anomaly is a sign of terminal illness. Perhaps in time I will overcome this paranoia.
Thank you very much again, and have a good evening!