In my opinion there was real cause for concern, with modest probability but very high stakes, not because of the properties of that monkeypox strain in itself, but for what it might have turned into if it sustained transmission on scale in humans and the new-host-driven evolution happened to carry it through phenotype territory closer to smallpox with respect to life cycle and virulence. Virulence levels of a less benign monkeypox lineage would have been bad enough actually, if the virus could tap into properties for effective transmission.
We seem to have lucked out about the evolution (again) this time, and it probably helped that the current version had agonizing symptoms and its transmission was best targeted to a human subpopulation which overall has a lot of healthy respect for epidemics.