The "go around" was initiated by the tower controller; therefore you can rule out any sort of equipment problems. This was likely done because there was something on the runway (aircraft, vehicle, animal, etc). and the aircraft may have not landed safely. Usually ATC will not declare a go around for an aircraft coming in too high however, they may ask the pilot if they want to go around. I think in this case (being that we weren't there it's hard to say), I think the runway was not clear.