I occasionally see ChangedBinaries reports that include
API Request failed
But it's incredibly difficult to track down why they failed, especially if it's one request amongst may successful ones.
Need to think of the best way around it, although including a timestamp with the error string would be a start.
To help track down the failed request, it might be worth including a unique serial number within the URI of the request to the API (sha1 of time() and hostname maybe?) and including that in the error message.
It'd then be easier to see whether the requests are getting through to the API and failing for some reason, or simply not reaching the API at all.