I'm not diagnosing here, but have you considered glasses? I'm at that age where I may soon have to get them or longer arms. I find that my face tightens very much during the same sort of activities as you've described. Just and idea.
However, when it comes to meditations, I have the opposite reaction. Once I close my eyes and start relaxing into a meditation my face begins to relax. Even before I start the meditation, my face starts relaxing. It continues to relax; almost in steps sometimes. Big reductions then relax and then some more. Instead a slower releasing action.
I can direct the relaxation with my thoughts. "Speaking in my mind" as Master Lin might say. I always find it helpful to synchronize the Relax thought with an exhale.
With practice it will work for you too. Maybe try working on a muscle you can consciously relax. Using it's behaviour as a good example for your face.
Another thought, just occured to me. That some people will "screw-up" their face when they try visualize, just as they would do if they were trying to SEE it. Maybe try the facial relaxation as a lying in the sun and getting a nice "safe" tan. Let the warmth of the sun, and the nothing to do attitude, melt the tension from your face.
You are perfection.
Iam2 
