If the power came on in your coach when the generator was started, you have an automatic transfer switch that switched the power supply from the shore line to the generator.
As long as the generator is running, the transfer switch keeps the shore line isolated from the coach and generator, even if shore power is restored. You do not need to unplug the shore line if the generator is running. It will switch back to the shore line when the generator is stopped whether there's shore power available or not.
Electrical codes require a disconnect in the line between utility power and a generator, either for household or RV's. This is to prevent your generator from backfeeding the utility lines and possibly electrocuting a lineman who is working on a line that is expected to be dead. This can be done with an automatic or manual transfer switch, or with a plug.
Some coaches have a receptacle wired from the generator instead of a transfer switch. With those coaches, you have to plug the shore line into the generator output receptacle.
2011 Sunseeker 3100
1997 Pathfinder Toad