My guess is that they had you test against the node which you are closest to, or the node that services your area. With my provider, in the terms, it mentions that speeds offered are taken from the closest node to my location. So that means, all their other nodes, which interconnect to the node that distributes to my area, could be problematic but as long as the node that is closest to me are fine, i'm SOL.
Do a tracert/nmap on speedtest.tampabay.rr.com against another server and you will see what i'm talking about.