Given our knowledge of physics, itthis must surely be a coincidence.
It so happens that $\pi$ can be experimentally observed, for instance by constructing circles out of wire. But there is a very biased causality here: The wire loop exhibits $\pi$ because our world is like the Platonic ideal of Euclidean sapcespace, not the other way around. Although it is worth noting that there is of course a reason why Euclid happened to start with exactly that kind of space, and not another.
You don't have to accept that $\pi_{earth}=\pi_{hell}=\pi_{alien}$. You can, for instance, make the disturbing but reasonable objection that mathematics is nothing but an artifact of the human brain, and is not universal but a posteriori. In a sense this position is weak, because we have observed animals to have a similar understanding of mathematics, but of course that is only circumstantial evidence, not proof.