It''s weird. It's always the same connection; the lug on the starter where the starter battery cable lands. I know this isn't your gremlin because your starter connection is fine. But it's almost always, every time, a bad connection in the circuit. Heat, changing moisture, and corrosion, some part of the circuit opens.

I clean that lug, the terminal, and I know it won't happen again this season. It will happen next spring, guaranteed.