Out of sync alert

[otterslide]

I believe in certain situations the full node can fall behind sync by at least one block, even though it shows synced, like a dust storm, and maybe even slow CPU. Just one block out of sync is likely to render the proof useless because it will come too late.
It would really help if there was some kind of warning that can detect this. One idea is to query a server at some time interval to get the latest block # and compare with the latest synced block in the logs. I'm not sure if such a server exists right now? It would be a fairly simple check that can be done once every 10-30min. If something is wrong with the Chia full node , such as running too slow, this would detect it.
A network condition like a dust storm could cause multiple full nodes to fall behind without knowing it also.