Change of Destination by aircraft in flight

I was recently tracking a flight in FlightAware and the destination said KGTU. However, when I checked the same flight in Flight Explorer, the destination was 40XS. 40XS was, in fact, the correct destination–I know the pilot and he changed his destination enroute. My question is, why did FlightAware not show the change? I was under the assumption that the source information was the same.