It's an early departure. Perhaps they are considering an AC swap or the AC is parked off a gate somewhere and hasn't received a gate assignment yet? It could be a number of things. GA's assigned to work the flight don't arrive at the departure gate until 1 hour before departure anyway. Why post a tentative assignment only to have it change? Just be patient. They'll either post it soon or post a delay. I hope for your sake it's the former and not the latter.

What's the flight number?