Over-tightened connections cause hot spots just like loose ones. Makes me wonder if the tech that fixed it last time was worried about loose connections and may have tightened it too much. The proper torque settings for neutral bar screws aren't all that high (usually 20-35 in.lbs depending on wire size).
Also if power was out for several hours then everyone's AC, water heaters, etc in the park and the fridges, freezers, etc on the wider grid all come on at the same time and cause the line voltage to sag. That could easily be what provided the stress to cause an already poor connection to fail.
2016 Jayflight 26BHS Elite
2014 F150 4x4 Super Crew, Eco-Boost, Max Tow
Bayliner Trophy 2002ff