This could have been a local grid issue, or it could have been that your battery had not yet reached optimum charging temperature. The charging speed displayed on the screen in MPH is affected by several variables. A more reliable indication of Supercharger function is the kW output.
Tesla does monitor all of the stations from its HQ and will dispatch a technician if a hardware problem is detected. In some out-of-the-way locations this can take several days. Obviously, they give the highest priority to stations where two or more chargers are out of service. Thanks to redundancy, the only scenario in which an entire station would be down is a grid failure.