"Should you worry?" Yes.

Green on filters is often either algae (not good) or copper (not good, either). You can find out by getting some bleach, some Vitamin C tabs, a couple of clear wine glasses, and some green sludge off your filter. Put a bit of the sludge in each glass, then add bleach to one. Add tap water + Vit. C to the other. If it's algae, the bleach will turn it brown. If it's copper, the Vit. C will cause the color to disappear or at least change.

. . . membership updated.