To clarify further - the cert was renewed 9 days before we got this warning.
We had not made any changes to the names on our cert, it has been the same for a long time.
So still not sure why it would send us this warning claiming it would expire soon. The only thing new/different as of late was that we had to re-install app a couple of weeks ago because it was failing to run. Once we did that, it did then work and renewed our cert.