I doubt it has anything specifically to do with filling the gas tank. What I would do is remove both battery cable connectors from the battery, thoroughly clean them with a wire brush, I reconnect them & make sure they are tight enough that you can't move the connector once it is secured to the battery post. They can wear & get loose enough that they can be moved even when the bolt is as tight as it can go.
A battery brush with a male & female parts made specifically for batteries is only $3-4 at any auto parts store. And your battery connections may LOOK fine but they may still be corroded internally or loose enough to cause this kind of a problem. Just visually inspecting the battery connections isn't enough, especially when you are having the type of starting problem you are experiencing.
Edit: It seems like you might have a prime suspect with the ignition kill but just in case, I'd clean the battery connections anyway.