Normal
I had my female P. cambridgei lay a phantom sac a few years ago. She was sexually mature at a smaller size than I expected. The sac contained 140 eggs. She cared for the sac for a few days as though it were fertile, but I eventually took it from her because she was on the thin side after creating the sac. I bribed her with a cricket and took it when she was distracted. She then ate all of the leftover webbing from the nest she created. Phantom sacs are a pretty common phenomenon in this genus that sometimes happens when the female reaches maturity. I also once had my AF T. stirmi create an infertile egg sac. That was a sight to behold. She could sense that it wasn't viable and almost immediately ate it.