I've never heard of a bike stalling or cutting out from overloading it. Possibly bad fuel...?...but I'd check out your connections at the relay, battery, grounds, fuse block, etc to be sure they're clean and solid. Years ago I failed to double check my battery terminals after the winter hibernation and had a corroded connection stall my ninja on a ride, so it's well worth the time to go over things. Dealers typically wont dig into a fix if they can't duplicate the problem, they may just chalk it up as operator error and send you home. Glad to hear you made it home ok, and hopefully the bike stays sorted out.