So, after some investigation, I think my shock is OK.
For convenience, I’ll condense the methodology and the findings together:
1 – Connect shock pump, set pressure to 260psi
2 – Cycle the shock to equalize chambers
3 – Final set pressure to 260psi
4 – Remove shock pump
5 – Re-connect shock pump and read – There it was, 240psi, 20psi loss
6 – Cycle the shock to equalize chambers, without removing pump
7 – read pressure after equalization – 245psi, 5 psi were gained after chamber equalization
8 – Set shock pressure
I repeated the procedure 3 times, always with the same results. I think this explains what I was observing. It seems that, discount the pump effect, the shock lost little to no pressure on my previous weekly readings