I think you're onto something. I did wonder about sciatica. Since getting Morton's Neuroma in the balls of my feet last year I'm still fairly active, but move much more slowly and carefully and that's caused tight calf muscles. Recently I've been doing calf muscle stretches, pulling the toes forward and holding, and it seems to help a bit.

I'll add your new more targeted stretch, thank you. I hadn't thought about tightness in other muscles too, but that makes sense.