So I've basically been ignoring the NOAA page, but when I just looked at it a minute ago, I noticed the tell-tale sign of a data outage: a big chunk of the graph was a nice straight line. Looking at the same graph on the CWOP page shows no such anomaly. So, it appears that I've bee successfully sending data to CWOP but, for half the day on Thursday, NOAA failed to retrieve it. Well, at least I now know that it's just not my problem!