Our stations are designed to be grid connected, so the only situation in which we'd expect them to be off grid would be either in a power failure or if they were used in a remote or off-grid community. For power, quality-wise, grid is best. We haven't heard many reports of that.
The one thing you might have seen, if it wasn't a generator, is that sometimes the fast-charging stations have a big separate piece of infrastructure that actually helps ensure the right voltage and amperage is coming. It could also have been that, or it might have been a temporary situation with the generator.