Fuel builds up static charge when it is pumped because of friction during fuel flow (and this may also happen during tanker or drum transport). That's why fuel tankers (or fuel pumping hydrant systems) and aircraft need to be properly earthed when being refueled to avoid excess static charge and particularly discharge of static which can cause vapours to ignite.
So sounds to me like this fuel has not been properly earthed at some points in its transport and handling and now has built up charge above what can be safely/conveniently discharged by the local infrastructure.
My source: 10 years as a RAAF Fuels Officer. They are right it is very rare - with proper handling, should not happen.