No documented occurence
In the same way there is no 'documented' evidence to prove it is safe.
Until it has been proven and confirmed that the use of mobile phones, etc are safe whilst engines are running on an aircraft, and that it is fine to use a mobile phone standing directly next to a fuel pump then it is best to keep them off.
After all, there was an original reason or theory behind the restriction of mobile phones in these places. It is doubted that it is safe to use them, and until it is proven otherwise, the rules will remain. Simple as that. Better to be safe than sorry. Under CAA regs in the UK passengers may use mobiles inside the aircraft whilst refuelling, and mobiles and electronic devices must be switched off when engines are running on any British registered aircraft. If an operator wants to tighten those rules, they can, providing it is agreed with the CAA.
a PA by Virgin CC at LHR las year that we couldn't use cellphones until inside the terminal "for security reasons" (this was after doors open).
Perhaps company policy, perhaps a personal attempt to avoid them being switched on prematurely. Who knows? I stopped flying with them when I had boarded a flight after 9/11 and during the delay due to additional security checks, a member of cabin crew felt it necessary to grafically remind passengers of the events of the fateful day, in far too much detail, resulting in many passengers in my area either looking worried or concerned, followed by one passenger asking to get off. Perhaps I was just unlucky on the day with who made the announcements.