Question
I recently purchased a paph of some sort from Trader Joe's. I brought it home and put it above my shower in my bathroom so it will get the highest humidity possible in So. Cal. and the light source is a small high west facing window. The plant is about 3 feet away from the window and gets the afternoon sunlight but the room is pretty dim the rest of the day. One of the lower leaves turned yellow and then brown and another one is just yellowing. Is this plant getting too much light, not enough light, or is it perhaps a temperature issue from the afternoon light?

Answer
My first thought is whether or nor the potting mix needs to be replaced.  This can be checked by unpotting your plant to make sure all of the roots are in good condition. Either way, I would repot it in a seedling type of orchid potting mix.

Most paphs prefer low to medium light and grow best in an east facing window or under lights so it may be getting too bright and/or too warm from the afternoon sun.

Finally, if you have a large plant, this may be just a natural process in which the oldest leaves are shed.  If you have just a few leaves, you probably should try growing it cooler in lower light.