Not sure if anyone heard it but I know it registered very clearly on barometers in London, so it's not out of the question.

It was apparently registered 3 times on Iceland (almost opposite side of earth) - apparently it was big enough to travel 3 times around the globe!

I was wondering the same thing. One factor might be the variation in propagation speed, which is visible for example due to winds near low pressure systems.

Another fact is the Earth is not a uniform sphere so the waves wouldn't exactly converge in a uniform circular condensation on that exact spot.

Unless you already factored that in...