Hopefully this is just a display bug. I have noticed it before myself.
Maybe someone made his battle then quitted the guild?
We were lacking one member when GW started and so on, we are only 29 members. But our counter always display X/150 instead of X/145…
I had the inverse of this glitch last week.
My guild had X/135 due to missing 3 people on Tuesday reset, but as we recruited back to full 30 members it showed X/150, despite us only having a max possible plays of 135.
This is a display bug that we are currently investigating.