Dimensional Nova

Was the Dimensional Nova the multiversal "explosion" of the universe Nexus saw a Lodestar killed in in an earlier book?

I'm listening to the audiobook after reading Chilling Reflections when it came out, so my memory is a little fuzzy, but I seem to recall Wade just saying "no one knows why these happen sometimes, but the less crazy people in the multiverse call it a dimensional nova".

I kind of feel like we have a clue Wade doesn't, and it's not actually mysterious at all.