Hmm, I think I solved the mystery of the cramping calf. When I get into my work/reading/whatever I stop paying attention to my body posture, and I just became aware of the fact that I was crossing my left leg over my right leg, whilst (Ah, always wanted to use that on here -'merican girls don't get to use whilst without being laughed at. Ahem, anyway...) balancing my right leg on my toes, and thus flexing my calf for god knows how long at a time. Only noticed because the calf started aching again. *sigh* I am special.