It seems to always be the same users, but I even tried having them go through a proxy server and they are still getting the error. Whenever I try the same request for the same location, though, it loads just fine. So I'm not really sure what's going on.
Here's one of their requests in case it helps: /v1/weather/en-US/42.047/-96.163?dataSets=currentWeather,forecastNextHour,forecastHourly,forecastDaily
And I submitted this as FB11577100 in case you need the ticket for internal tracking purposes.