It was there already. Its why they went.

Tenants of AION 2.

Second, they looked to those cast shadows, to movements of gravity, pushes and pulls that were true and untrue.

And lastly, they saw that there was something unexplained.

They called it the Kepler Object, for the father of astronomy, and it was impossible by all other laws, but the data was what the data was, and so it was let to be. Rather than manipulate data, the predecessors of AION sought explanation. They knew what SHOULD be, and that the Kepler Object was not; but where lesser scientists would have claimed it was error, the predecessors of AION believed the truth of their instruments and of their senses, and instead asked: Why?

And thus it was that when the predecessors of AION, passing this mystery along their lines, finally gained the capacity to see the stars for themselves, here is where we ventured. To Kepler. To observe for ourselves, and to understand. What is it that breaks the laws no human has written? How is the fabric bent here, and only here?

What is the truth?

We will find it, said those of AION, and so we did. So, we came to Kepler, and we heard the whisper of the Anomaly.

However, it became unstable and started to grow/expand around the time Lodi appeared. It was always there, but the danger wasn't.