Hey Stuart, here's a quick update - the gap has closed by up by it's own accord in the two weeks since this happened.

To answer your question, yes the joint went together perfectly with the test fit, and again perfectly with the glue-up. Some on here have suggested the joint might have been clamped too tightly and that pushed most of the epoxy out, and I think I agree with them.

I might run some thin CA glue into the joint before finishing the top. I tested CA glue on epoxy and it seems to adhere pretty well.