Hmmm this is the 1st time I have heard of this but during multiple attempts to "reach" my SI nerve they have "inavertantly" triggered nerves in my abd and in my rib area. When I reported where the sensation was occuring the immeadiatly turned off whatever they had turned on (each one of my leads has like 16 electrodes along it). So maybe yhis is similat 2 what happened 2 you?