Even with the pool covered it's pretty amazing to only drop from 5 ppm FC to 4.5 ppm FC over 2 weeks. That usually only happens when the water is much colder -- is the water cold now?

As for pH, I don't know what you mean by an anemic color. It's the hue that matters in terms of the pH test, not the intensity of the color. So is it yellowish or is it pinkish? As water gets colder, the pH will naturally rise a little bit. When the water warms up, the pH drops back down. Over extended periods of time even with a pool cover one can have some carbon dioxide outgassing making the pH rise.

Anyway, regardless of the source, it seems that one should check their chlorine and pH levels at least once a month even when the water is very cold (when one doesn't close by draining below skimmer and returns for winterizing, etc.).

In my own pool, I found that the pH rose over the winter, but every pool is different.