it won't directly hurt anything, but it can spread and physically block light and flow to your corals. Just manually remove some regularly with a razor blade to keep it in check!
Not sure what you have but my Sea Grapes (caulerpa lentillifera(sp)) grow similar and I do not have any issues. I keep it in my refugium for a natural source of food for my rabbitfish and scopas tang. They love the stuff. I can reach in, grab a handful, rubberband it, toss in the display, and it will be gone in short order. My copperband and milletseed pick at it as well looking for aiptasia, pods, and worms.
Will it hurt? No. Can it overgrow? Sure. Just find an amount you are happy with and manage it. Bonus if you have animals that eat it.