IMO it doesn't seem like there is much solid evidence there. But it's not clear to me if this was picked up by one or two sensors.

What I wonder about, is this:

Update: 6/7/12, 7:45 A.M: - False Alert: The alert level reading last evening appears to be a false alert from an equipment malfunction. Here is the station's report:

"out of control readings on the GeigerGraph screen from about 11:30pm local time that occurred while sleeping. My apologies to all. I have no idea what caused this. Shut down GeigerGraph and restarted. Readings from the Geiger were in the normal range (the Geiger operates on A/C). All cable connections are tight and not loose. Am speculating between the GFI and USB Adapter and some sort of voltage spikes. The uninterruptable power supply UPS had lost power and had died - a tripped GFI. I am not going to leave the system running while not at home until I can determine and fix the problem."

By the way, a handful of stations on the Radiation Network feed simultaneously to the Black Cat Systems network, which explains why a high reading was showing on their network at the same time. But Black Cat works in uR/hr instead of CPM, so their radiation level was lower because of the conversion factor between units of measurement.

It says that BlackCat works in uR/hr, but the one I see is CPM and peaked around 3500.

That said, Geiger counters are a pretty basic technology. It would be great for something like BlackCat to expand into a much larger public network.