Onan 7k gas generator - long cranking time on re-start

If it was just running recently, you shouldn't need to reprime the generator. I don't think on the usual Onan setup it would cause problems (e.g. flooding) since it's really just filling the carb bowl with fuel and extracting any air from the gas lines, but on other engine designs it very well could cause flooding, just as using the choke could.

Perhaps you're encountering mild vapor lock?